1 # SPDX-License-Identifier: GPL-2.0+
2 #
3 # (C) Copyright 2000 - 2013
4 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
6 Summary:
7 ========
9 This directory contains the source code for U-Boot, a boot loader for
10 Embedded boards based on PowerPC, ARM, MIPS and several other
11 processors, which can be installed in a boot ROM and used to
12 initialize and test the hardware or to download and run application
13 code.
15 The development of U-Boot is closely related to Linux: some parts of
16 the source code originate in the Linux source tree, we have some
17 header files in common, and special provision has been made to
18 support booting of Linux images.
20 Some attention has been paid to make this software easily
21 configurable and extendable. For instance, all monitor commands are
22 implemented with the same call interface, so that it's very easy to
23 add new commands. Also, instead of permanently adding rarely used
24 code (for instance hardware test utilities) to the monitor, you can
25 load and run it dynamically.
28 Status:
29 =======
31 In general, all boards for which a configuration option exists in the
32 Makefile have been tested to some extent and can be considered
33 "working". In fact, many of them are used in production systems.
35 In case of problems see the CHANGELOG file to find out who contributed
36 the specific port. In addition, there are various MAINTAINERS files
37 scattered throughout the U-Boot source identifying the people or
38 companies responsible for various boards and subsystems.
40 Note: As of August, 2010, there is no longer a CHANGELOG file in the
41 actual U-Boot source tree; however, it can be created dynamically
42 from the Git log using:
44 make CHANGELOG
47 Where to get help:
48 ==================
50 In case you have questions about, problems with or contributions for
51 U-Boot, you should send a message to the U-Boot mailing list at
52 <u-boot@lists.denx.de>. There is also an archive of previous traffic
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see http://lists.denx.de/pipermail/u-boot and
55 http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
58 Where to get source code:
59 =========================
61 The U-Boot source code is maintained in the Git repository at
62 git://www.denx.de/git/u-boot.git ; you can browse it online at
63 http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
65 The "snapshot" links on this page allow you to download tarballs of
66 any version you might be interested in. Official releases are also
67 available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
68 directory.
70 Pre-built (and tested) images are available from
71 ftp://ftp.denx.de/pub/u-boot/images/
74 Where we come from:
75 ===================
77 - start from 8xxrom sources
78 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
79 - clean up code
80 - make it easier to add custom boards
81 - make it possible to add other [PowerPC] CPUs
82 - extend functions, especially:
83 * Provide extended interface to Linux boot loader
84 * S-Record download
85 * network boot
86 * ATA disk / SCSI ... boot
87 - create ARMBoot project (http://sourceforge.net/projects/armboot)
88 - add other CPU families (starting with ARM)
89 - create U-Boot project (http://sourceforge.net/projects/u-boot)
90 - current project page: see http://www.denx.de/wiki/U-Boot
93 Names and Spelling:
94 ===================
96 The "official" name of this project is "Das U-Boot". The spelling
97 "U-Boot" shall be used in all written text (documentation, comments
98 in source files etc.). Example:
100 This is the README file for the U-Boot project.
102 File names etc. shall be based on the string "u-boot". Examples:
104 include/asm-ppc/u-boot.h
106 #include <asm/u-boot.h>
108 Variable names, preprocessor constants etc. shall be either based on
109 the string "u_boot" or on "U_BOOT". Example:
111 U_BOOT_VERSION u_boot_logo
112 IH_OS_U_BOOT u_boot_hush_start
115 Versioning:
116 ===========
118 Starting with the release in October 2008, the names of the releases
119 were changed from numerical release numbers without deeper meaning
120 into a time stamp based numbering. Regular releases are identified by
121 names consisting of the calendar year and month of the release date.
122 Additional fields (if present) indicate release candidates or bug fix
123 releases in "stable" maintenance trees.
125 Examples:
126 U-Boot v2009.11 - Release November 2009
127 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
128 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
131 Directory Hierarchy:
132 ====================
134 /arch Architecture specific files
135 /arc Files generic to ARC architecture
136 /arm Files generic to ARM architecture
137 /m68k Files generic to m68k architecture
138 /microblaze Files generic to microblaze architecture
139 /mips Files generic to MIPS architecture
140 /nds32 Files generic to NDS32 architecture
141 /nios2 Files generic to Altera NIOS2 architecture
142 /openrisc Files generic to OpenRISC architecture
143 /powerpc Files generic to PowerPC architecture
144 /riscv Files generic to RISC-V architecture
145 /sandbox Files generic to HW-independent "sandbox"
146 /sh Files generic to SH architecture
147 /x86 Files generic to x86 architecture
148 /api Machine/arch independent API for external apps
149 /board Board dependent files
150 /cmd U-Boot commands functions
151 /common Misc architecture independent functions
152 /configs Board default configuration files
153 /disk Code for disk drive partition handling
154 /doc Documentation (don't expect too much)
155 /drivers Commonly used device drivers
156 /dts Contains Makefile for building internal U-Boot fdt.
157 /examples Example code for standalone applications, etc.
158 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
159 /include Header Files
160 /lib Library routines generic to all architectures
161 /Licenses Various license files
162 /net Networking code
163 /post Power On Self Test
164 /scripts Various build scripts and Makefiles
165 /test Various unit test files
166 /tools Tools to build S-Record or U-Boot images, etc.
168 Software Configuration:
169 =======================
171 Configuration is usually done using C preprocessor defines; the
172 rationale behind that is to avoid dead code whenever possible.
174 There are two classes of configuration variables:
176 * Configuration _OPTIONS_:
177 These are selectable by the user and have names beginning with
178 "CONFIG_".
180 * Configuration _SETTINGS_:
181 These depend on the hardware etc. and should not be meddled with if
182 you don't know what you're doing; they have names beginning with
183 "CONFIG_SYS_".
185 Previously, all configuration was done by hand, which involved creating
186 symbolic links and editing configuration files manually. More recently,
187 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
188 allowing you to use the "make menuconfig" command to configure your
189 build.
192 Selection of Processor Architecture and Board Type:
193 ---------------------------------------------------
195 For all supported boards there are ready-to-use default
196 configurations available; just type "make <board_name>_defconfig".
198 Example: For a TQM823L module type:
200 cd u-boot
201 make TQM823L_defconfig
203 Note: If you're looking for the default configuration file for a board
204 you're sure used to be there but is now missing, check the file
205 doc/README.scrapyard for a list of no longer supported boards.
207 Sandbox Environment:
208 --------------------
210 U-Boot can be built natively to run on a Linux host using the 'sandbox'
211 board. This allows feature development which is not board- or architecture-
212 specific to be undertaken on a native platform. The sandbox is also used to
213 run some of U-Boot's tests.
215 See doc/arch/index.rst for more details.
218 Board Initialisation Flow:
219 --------------------------
221 This is the intended start-up flow for boards. This should apply for both
222 SPL and U-Boot proper (i.e. they both follow the same rules).
224 Note: "SPL" stands for "Secondary Program Loader," which is explained in
225 more detail later in this file.
227 At present, SPL mostly uses a separate code path, but the function names
228 and roles of each function are the same. Some boards or architectures
229 may not conform to this. At least most ARM boards which use
230 CONFIG_SPL_FRAMEWORK conform to this.
232 Execution typically starts with an architecture-specific (and possibly
233 CPU-specific) start.S file, such as:
235 - arch/arm/cpu/armv7/start.S
236 - arch/powerpc/cpu/mpc83xx/start.S
237 - arch/mips/cpu/start.S
239 and so on. From there, three functions are called; the purpose and
240 limitations of each of these functions are described below.
242 lowlevel_init():
243 - purpose: essential init to permit execution to reach board_init_f()
244 - no global_data or BSS
245 - there is no stack (ARMv7 may have one but it will soon be removed)
246 - must not set up SDRAM or use console
247 - must only do the bare minimum to allow execution to continue to
248 board_init_f()
249 - this is almost never needed
250 - return normally from this function
252 board_init_f():
253 - purpose: set up the machine ready for running board_init_r():
254 i.e. SDRAM and serial UART
255 - global_data is available
256 - stack is in SRAM
257 - BSS is not available, so you cannot use global/static variables,
258 only stack variables and global_data
260 Non-SPL-specific notes:
261 - dram_init() is called to set up DRAM. If already done in SPL this
262 can do nothing
264 SPL-specific notes:
265 - you can override the entire board_init_f() function with your own
266 version as needed.
267 - preloader_console_init() can be called here in extremis
268 - should set up SDRAM, and anything needed to make the UART work
269 - there is no need to clear BSS, it will be done by crt0.S
270 - for specific scenarios on certain architectures an early BSS *can*
271 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
272 of BSS prior to entering board_init_f()) but doing so is discouraged.
273 Instead it is strongly recommended to architect any code changes
274 or additions such to not depend on the availability of BSS during
275 board_init_f() as indicated in other sections of this README to
276 maintain compatibility and consistency across the entire code base.
277 - must return normally from this function (don't call board_init_r()
278 directly)
280 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
281 this point the stack and global_data are relocated to below
282 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
283 memory.
285 board_init_r():
286 - purpose: main execution, common code
287 - global_data is available
288 - SDRAM is available
289 - BSS is available, all static/global variables can be used
290 - execution eventually continues to main_loop()
292 Non-SPL-specific notes:
293 - U-Boot is relocated to the top of memory and is now running from
294 there.
296 SPL-specific notes:
297 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
298 CONFIG_SPL_STACK_R_ADDR points into SDRAM
299 - preloader_console_init() can be called here - typically this is
300 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
301 spl_board_init() function containing this call
302 - loads U-Boot or (in falcon mode) Linux
306 Configuration Options:
307 ----------------------
309 Configuration depends on the combination of board and CPU type; all
310 such information is kept in a configuration file
311 "include/configs/<board_name>.h".
313 Example: For a TQM823L module, all configuration settings are in
314 "include/configs/TQM823L.h".
317 Many of the options are named exactly as the corresponding Linux
318 kernel configuration options. The intention is to make it easier to
319 build a config tool - later.
321 - ARM Platform Bus Type(CCI):
322 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
323 provides full cache coherency between two clusters of multi-core
324 CPUs and I/O coherency for devices and I/O masters
326 CONFIG_SYS_FSL_HAS_CCI400
328 Defined For SoC that has cache coherent interconnect
329 CCN-400
331 CONFIG_SYS_FSL_HAS_CCN504
333 Defined for SoC that has cache coherent interconnect CCN-504
335 The following options need to be configured:
337 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
339 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
341 - 85xx CPU Options:
342 CONFIG_SYS_PPC64
344 Specifies that the core is a 64-bit PowerPC implementation (implements
345 the "64" category of the Power ISA). This is necessary for ePAPR
346 compliance, among other possible reasons.
348 CONFIG_SYS_FSL_TBCLK_DIV
350 Defines the core time base clock divider ratio compared to the
351 system clock. On most PQ3 devices this is 8, on newer QorIQ
352 devices it can be 16 or 32. The ratio varies from SoC to Soc.
354 CONFIG_SYS_FSL_PCIE_COMPAT
356 Defines the string to utilize when trying to match PCIe device
357 tree nodes for the given platform.
359 CONFIG_SYS_FSL_ERRATUM_A004510
361 Enables a workaround for erratum A004510. If set,
362 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
363 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
365 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
366 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
368 Defines one or two SoC revisions (low 8 bits of SVR)
369 for which the A004510 workaround should be applied.
371 The rest of SVR is either not relevant to the decision
372 of whether the erratum is present (e.g. p2040 versus
373 p2041) or is implied by the build target, which controls
374 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
376 See Freescale App Note 4493 for more information about
377 this erratum.
379 CONFIG_A003399_NOR_WORKAROUND
380 Enables a workaround for IFC erratum A003399. It is only
381 required during NOR boot.
383 CONFIG_A008044_WORKAROUND
384 Enables a workaround for T1040/T1042 erratum A008044. It is only
385 required during NAND boot and valid for Rev 1.0 SoC revision
387 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
389 This is the value to write into CCSR offset 0x18600
390 according to the A004510 workaround.
392 CONFIG_SYS_FSL_DSP_DDR_ADDR
393 This value denotes start offset of DDR memory which is
394 connected exclusively to the DSP cores.
396 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
397 This value denotes start offset of M2 memory
398 which is directly connected to the DSP core.
400 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
401 This value denotes start offset of M3 memory which is directly
402 connected to the DSP core.
404 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
405 This value denotes start offset of DSP CCSR space.
407 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
408 Single Source Clock is clocking mode present in some of FSL SoC's.
409 In this mode, a single differential clock is used to supply
410 clocks to the sysclock, ddrclock and usbclock.
412 CONFIG_SYS_CPC_REINIT_F
413 This CONFIG is defined when the CPC is configured as SRAM at the
414 time of U-Boot entry and is required to be re-initialized.
416 CONFIG_DEEP_SLEEP
417 Indicates this SoC supports deep sleep feature. If deep sleep is
418 supported, core will start to execute uboot when wakes up.
420 - Generic CPU options:
421 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
423 Defines the endianess of the CPU. Implementation of those
424 values is arch specific.
426 CONFIG_SYS_FSL_DDR
427 Freescale DDR driver in use. This type of DDR controller is
428 found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
429 SoCs.
431 CONFIG_SYS_FSL_DDR_ADDR
432 Freescale DDR memory-mapped register base.
434 CONFIG_SYS_FSL_DDR_EMU
435 Specify emulator support for DDR. Some DDR features such as
436 deskew training are not available.
438 CONFIG_SYS_FSL_DDRC_GEN1
439 Freescale DDR1 controller.
441 CONFIG_SYS_FSL_DDRC_GEN2
442 Freescale DDR2 controller.
444 CONFIG_SYS_FSL_DDRC_GEN3
445 Freescale DDR3 controller.
447 CONFIG_SYS_FSL_DDRC_GEN4
448 Freescale DDR4 controller.
450 CONFIG_SYS_FSL_DDRC_ARM_GEN3
451 Freescale DDR3 controller for ARM-based SoCs.
453 CONFIG_SYS_FSL_DDR1
454 Board config to use DDR1. It can be enabled for SoCs with
455 Freescale DDR1 or DDR2 controllers, depending on the board
456 implemetation.
458 CONFIG_SYS_FSL_DDR2
459 Board config to use DDR2. It can be enabled for SoCs with
460 Freescale DDR2 or DDR3 controllers, depending on the board
461 implementation.
463 CONFIG_SYS_FSL_DDR3
464 Board config to use DDR3. It can be enabled for SoCs with
465 Freescale DDR3 or DDR3L controllers.
467 CONFIG_SYS_FSL_DDR3L
468 Board config to use DDR3L. It can be enabled for SoCs with
469 DDR3L controllers.
471 CONFIG_SYS_FSL_DDR4
472 Board config to use DDR4. It can be enabled for SoCs with
473 DDR4 controllers.
475 CONFIG_SYS_FSL_IFC_BE
476 Defines the IFC controller register space as Big Endian
478 CONFIG_SYS_FSL_IFC_LE
479 Defines the IFC controller register space as Little Endian
481 CONFIG_SYS_FSL_IFC_CLK_DIV
482 Defines divider of platform clock(clock input to IFC controller).
484 CONFIG_SYS_FSL_LBC_CLK_DIV
485 Defines divider of platform clock(clock input to eLBC controller).
487 CONFIG_SYS_FSL_PBL_PBI
488 It enables addition of RCW (Power on reset configuration) in built image.
489 Please refer doc/README.pblimage for more details
491 CONFIG_SYS_FSL_PBL_RCW
492 It adds PBI(pre-boot instructions) commands in u-boot build image.
493 PBI commands can be used to configure SoC before it starts the execution.
494 Please refer doc/README.pblimage for more details
496 CONFIG_SYS_FSL_DDR_BE
497 Defines the DDR controller register space as Big Endian
499 CONFIG_SYS_FSL_DDR_LE
500 Defines the DDR controller register space as Little Endian
502 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
503 Physical address from the view of DDR controllers. It is the
504 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
505 it could be different for ARM SoCs.
507 CONFIG_SYS_FSL_DDR_INTLV_256B
508 DDR controller interleaving on 256-byte. This is a special
509 interleaving mode, handled by Dickens for Freescale layerscape
510 SoCs with ARM core.
512 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
513 Number of controllers used as main memory.
515 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
516 Number of controllers used for other than main memory.
518 CONFIG_SYS_FSL_HAS_DP_DDR
519 Defines the SoC has DP-DDR used for DPAA.
521 CONFIG_SYS_FSL_SEC_BE
522 Defines the SEC controller register space as Big Endian
524 CONFIG_SYS_FSL_SEC_LE
525 Defines the SEC controller register space as Little Endian
527 - MIPS CPU options:
528 CONFIG_SYS_INIT_SP_OFFSET
530 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
531 pointer. This is needed for the temporary stack before
532 relocation.
534 CONFIG_XWAY_SWAP_BYTES
536 Enable compilation of tools/xway-swap-bytes needed for Lantiq
537 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
538 be swapped if a flash programmer is used.
540 - ARM options:
541 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
543 Select high exception vectors of the ARM core, e.g., do not
544 clear the V bit of the c1 register of CP15.
546 COUNTER_FREQUENCY
547 Generic timer clock source frequency.
549 COUNTER_FREQUENCY_REAL
550 Generic timer clock source frequency if the real clock is
551 different from COUNTER_FREQUENCY, and can only be determined
552 at run time.
554 - Tegra SoC options:
555 CONFIG_TEGRA_SUPPORT_NON_SECURE
557 Support executing U-Boot in non-secure (NS) mode. Certain
558 impossible actions will be skipped if the CPU is in NS mode,
559 such as ARM architectural timer initialization.
561 - Linux Kernel Interface:
562 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
564 When transferring memsize parameter to Linux, some versions
565 expect it to be in bytes, others in MB.
566 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
568 CONFIG_OF_LIBFDT
570 New kernel versions are expecting firmware settings to be
571 passed using flattened device trees (based on open firmware
572 concepts).
574 CONFIG_OF_LIBFDT
575 * New libfdt-based support
576 * Adds the "fdt" command
577 * The bootm command automatically updates the fdt
579 OF_TBCLK - The timebase frequency.
580 OF_STDOUT_PATH - The path to the console device
582 boards with QUICC Engines require OF_QE to set UCC MAC
583 addresses
585 CONFIG_OF_BOARD_SETUP
587 Board code has addition modification that it wants to make
588 to the flat device tree before handing it off to the kernel
590 CONFIG_OF_SYSTEM_SETUP
592 Other code has addition modification that it wants to make
593 to the flat device tree before handing it off to the kernel.
594 This causes ft_system_setup() to be called before booting
595 the kernel.
597 CONFIG_OF_IDE_FIXUP
599 U-Boot can detect if an IDE device is present or not.
600 If not, and this new config option is activated, U-Boot
601 removes the ATA node from the DTS before booting Linux,
602 so the Linux IDE driver does not probe the device and
603 crash. This is needed for buggy hardware (uc101) where
604 no pull down resistor is connected to the signal IDE5V_DD7.
606 CONFIG_MACH_TYPE [relevant for ARM only][mandatory]
608 This setting is mandatory for all boards that have only one
609 machine type and must be used to specify the machine type
610 number as it appears in the ARM machine registry
611 (see http://www.arm.linux.org.uk/developer/machines/).
612 Only boards that have multiple machine types supported
613 in a single configuration file and the machine type is
614 runtime discoverable, do not have to use this setting.
616 - vxWorks boot parameters:
618 bootvx constructs a valid bootline using the following
619 environments variables: bootdev, bootfile, ipaddr, netmask,
620 serverip, gatewayip, hostname, othbootargs.
621 It loads the vxWorks image pointed bootfile.
623 Note: If a "bootargs" environment is defined, it will overwride
624 the defaults discussed just above.
626 - Cache Configuration:
627 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
629 - Cache Configuration for ARM:
630 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
631 controller
632 CONFIG_SYS_PL310_BASE - Physical base address of PL310
633 controller register space
635 - Serial Ports:
636 CONFIG_PL010_SERIAL
638 Define this if you want support for Amba PrimeCell PL010 UARTs.
640 CONFIG_PL011_SERIAL
642 Define this if you want support for Amba PrimeCell PL011 UARTs.
644 CONFIG_PL011_CLOCK
646 If you have Amba PrimeCell PL011 UARTs, set this variable to
647 the clock speed of the UARTs.
649 CONFIG_PL01x_PORTS
651 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
652 define this to a list of base addresses for each (supported)
653 port. See e.g. include/configs/versatile.h
655 CONFIG_SERIAL_HW_FLOW_CONTROL
657 Define this variable to enable hw flow control in serial driver.
658 Current user of this option is drivers/serial/nsl16550.c driver
660 - Autoboot Command:
661 CONFIG_BOOTCOMMAND
662 Only needed when CONFIG_BOOTDELAY is enabled;
663 define a command string that is automatically executed
664 when no character is read on the console interface
665 within "Boot Delay" after reset.
667 CONFIG_RAMBOOT and CONFIG_NFSBOOT
668 The value of these goes into the environment as
669 "ramboot" and "nfsboot" respectively, and can be used
670 as a convenience, when switching between booting from
671 RAM and NFS.
673 - Serial Download Echo Mode:
674 CONFIG_LOADS_ECHO
675 If defined to 1, all characters received during a
676 serial download (using the "loads" command) are
677 echoed back. This might be needed by some terminal
678 emulations (like "cu"), but may as well just take
679 time on others. This setting #define's the initial
680 value of the "loads_echo" environment variable.
682 - Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
683 CONFIG_KGDB_BAUDRATE
684 Select one of the baudrates listed in
685 CONFIG_SYS_BAUDRATE_TABLE, see below.
687 - Removal of commands
688 If no commands are needed to boot, you can disable
689 CONFIG_CMDLINE to remove them. In this case, the command line
690 will not be available, and when U-Boot wants to execute the
691 boot command (on start-up) it will call board_run_command()
692 instead. This can reduce image size significantly for very
693 simple boot procedures.
695 - Regular expression support:
696 CONFIG_REGEX
697 If this variable is defined, U-Boot is linked against
698 the SLRE (Super Light Regular Expression) library,
699 which adds regex support to some commands, as for
700 example "env grep" and "setexpr".
702 - Device tree:
703 CONFIG_OF_CONTROL
704 If this variable is defined, U-Boot will use a device tree
705 to configure its devices, instead of relying on statically
706 compiled #defines in the board file. This option is
707 experimental and only available on a few boards. The device
708 tree is available in the global data as gd->fdt_blob.
710 U-Boot needs to get its device tree from somewhere. This can
711 be done using one of the three options below:
713 CONFIG_OF_EMBED
714 If this variable is defined, U-Boot will embed a device tree
715 binary in its image. This device tree file should be in the
716 board directory and called <soc>-<board>.dts. The binary file
717 is then picked up in board_init_f() and made available through
718 the global data structure as gd->fdt_blob.
720 CONFIG_OF_SEPARATE
721 If this variable is defined, U-Boot will build a device tree
722 binary. It will be called u-boot.dtb. Architecture-specific
723 code will locate it at run-time. Generally this works by:
725 cat u-boot.bin u-boot.dtb >image.bin
727 and in fact, U-Boot does this for you, creating a file called
728 u-boot-dtb.bin which is useful in the common case. You can
729 still use the individual files if you need something more
730 exotic.
732 CONFIG_OF_BOARD
733 If this variable is defined, U-Boot will use the device tree
734 provided by the board at runtime instead of embedding one with
735 the image. Only boards defining board_fdt_blob_setup() support
736 this option (see include/fdtdec.h file).
738 - Watchdog:
739 CONFIG_WATCHDOG
740 If this variable is defined, it enables watchdog
741 support for the SoC. There must be support in the SoC
742 specific code for a watchdog. For the 8xx
743 CPUs, the SIU Watchdog feature is enabled in the SYPCR
744 register. When supported for a specific SoC is
745 available, then no further board specific code should
746 be needed to use it.
748 CONFIG_HW_WATCHDOG
749 When using a watchdog circuitry external to the used
750 SoC, then define this variable and provide board
751 specific code for the "hw_watchdog_reset" function.
753 - Real-Time Clock:
755 When CONFIG_CMD_DATE is selected, the type of the RTC
756 has to be selected, too. Define exactly one of the
757 following options:
759 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
760 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
761 CONFIG_RTC_MC146818 - use MC146818 RTC
762 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
763 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
764 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
765 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
766 CONFIG_RTC_DS164x - use Dallas DS164x RTC
767 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
768 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
769 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
770 CONFIG_SYS_RV3029_TCR - enable trickle charger on
771 RV3029 RTC.
773 Note that if the RTC uses I2C, then the I2C interface
774 must also be configured. See I2C Support, below.
776 - GPIO Support:
777 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
779 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
780 chip-ngpio pairs that tell the PCA953X driver the number of
781 pins supported by a particular chip.
783 Note that if the GPIO device uses I2C, then the I2C interface
784 must also be configured. See I2C Support, below.
786 - I/O tracing:
787 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
788 accesses and can checksum them or write a list of them out
789 to memory. See the 'iotrace' command for details. This is
790 useful for testing device drivers since it can confirm that
791 the driver behaves the same way before and after a code
792 change. Currently this is supported on sandbox and arm. To
793 add support for your architecture, add '#include <iotrace.h>'
794 to the bottom of arch/<arch>/include/asm/io.h and test.
796 Example output from the 'iotrace stats' command is below.
797 Note that if the trace buffer is exhausted, the checksum will
798 still continue to operate.
800 iotrace is enabled
801 Start: 10000000 (buffer start address)
802 Size: 00010000 (buffer size)
803 Offset: 00000120 (current buffer offset)
804 Output: 10000120 (start + offset)
805 Count: 00000018 (number of trace records)
806 CRC32: 9526fb66 (CRC32 of all trace records)
808 - Timestamp Support:
810 When CONFIG_TIMESTAMP is selected, the timestamp
811 (date and time) of an image is printed by image
812 commands like bootm or iminfo. This option is
813 automatically enabled when you select CONFIG_CMD_DATE .
815 - Partition Labels (disklabels) Supported:
816 Zero or more of the following:
817 CONFIG_MAC_PARTITION Apple's MacOS partition table.
818 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
819 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
820 bootloader. Note 2TB partition limit; see
821 disk/part_efi.c
822 CONFIG_SCSI) you must configure support for at
823 least one non-MTD partition type as well.
825 - IDE Reset method:
826 CONFIG_IDE_RESET_ROUTINE - this is defined in several
827 board configurations files but used nowhere!
829 CONFIG_IDE_RESET - is this is defined, IDE Reset will
830 be performed by calling the function
831 ide_set_reset(int reset)
832 which has to be defined in a board specific file
834 - ATAPI Support:
835 CONFIG_ATAPI
837 Set this to enable ATAPI support.
839 - LBA48 Support
840 CONFIG_LBA48
842 Set this to enable support for disks larger than 137GB
843 Also look at CONFIG_SYS_64BIT_LBA.
844 Whithout these , LBA48 support uses 32bit variables and will 'only'
845 support disks up to 2.1TB.
847 CONFIG_SYS_64BIT_LBA:
848 When enabled, makes the IDE subsystem use 64bit sector addresses.
849 Default is 32bit.
851 - SCSI Support:
852 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
853 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
854 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
855 maximum numbers of LUNs, SCSI ID's and target
856 devices.
858 The environment variable 'scsidevs' is set to the number of
859 SCSI devices found during the last scan.
861 - NETWORK Support (PCI):
862 CONFIG_E1000
863 Support for Intel 8254x/8257x gigabit chips.
865 CONFIG_E1000_SPI
866 Utility code for direct access to the SPI bus on Intel 8257x.
867 This does not do anything useful unless you set at least one
868 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
870 CONFIG_E1000_SPI_GENERIC
871 Allow generic access to the SPI bus on the Intel 8257x, for
872 example with the "sspi" command.
874 CONFIG_NATSEMI
875 Support for National dp83815 chips.
877 CONFIG_NS8382X
878 Support for National dp8382[01] gigabit chips.
880 - NETWORK Support (other):
882 CONFIG_DRIVER_AT91EMAC
883 Support for AT91RM9200 EMAC.
885 CONFIG_RMII
886 Define this to use reduced MII inteface
888 CONFIG_DRIVER_AT91EMAC_QUIET
889 If this defined, the driver is quiet.
890 The driver doen't show link status messages.
892 CONFIG_CALXEDA_XGMAC
893 Support for the Calxeda XGMAC device
895 CONFIG_LAN91C96
896 Support for SMSC's LAN91C96 chips.
898 CONFIG_LAN91C96_USE_32_BIT
899 Define this to enable 32 bit addressing
901 CONFIG_SMC91111
902 Support for SMSC's LAN91C111 chip
904 CONFIG_SMC91111_BASE
905 Define this to hold the physical address
906 of the device (I/O space)
908 CONFIG_SMC_USE_32_BIT
909 Define this if data bus is 32 bits
911 CONFIG_SMC_USE_IOFUNCS
912 Define this to use i/o functions instead of macros
913 (some hardware wont work with macros)
915 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
916 Define this if you have more then 3 PHYs.
918 CONFIG_FTGMAC100
919 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
921 CONFIG_FTGMAC100_EGIGA
922 Define this to use GE link update with gigabit PHY.
923 Define this if FTGMAC100 is connected to gigabit PHY.
924 If your system has 10/100 PHY only, it might not occur
925 wrong behavior. Because PHY usually return timeout or
926 useless data when polling gigabit status and gigabit
927 control registers. This behavior won't affect the
928 correctnessof 10/100 link speed update.
930 CONFIG_SH_ETHER
931 Support for Renesas on-chip Ethernet controller
933 CONFIG_SH_ETHER_USE_PORT
934 Define the number of ports to be used
936 CONFIG_SH_ETHER_PHY_ADDR
937 Define the ETH PHY's address
939 CONFIG_SH_ETHER_CACHE_WRITEBACK
940 If this option is set, the driver enables cache flush.
942 - TPM Support:
943 CONFIG_TPM
944 Support TPM devices.
946 CONFIG_TPM_TIS_INFINEON
947 Support for Infineon i2c bus TPM devices. Only one device
948 per system is supported at this time.
950 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
951 Define the burst count bytes upper limit
953 CONFIG_TPM_ST33ZP24
954 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
956 CONFIG_TPM_ST33ZP24_I2C
957 Support for STMicroelectronics ST33ZP24 I2C devices.
958 Requires TPM_ST33ZP24 and I2C.
960 CONFIG_TPM_ST33ZP24_SPI
961 Support for STMicroelectronics ST33ZP24 SPI devices.
962 Requires TPM_ST33ZP24 and SPI.
964 CONFIG_TPM_ATMEL_TWI
965 Support for Atmel TWI TPM device. Requires I2C support.
967 CONFIG_TPM_TIS_LPC
968 Support for generic parallel port TPM devices. Only one device
969 per system is supported at this time.
971 CONFIG_TPM_TIS_BASE_ADDRESS
972 Base address where the generic TPM device is mapped
973 to. Contemporary x86 systems usually map it at
974 0xfed40000.
976 CONFIG_TPM
977 Define this to enable the TPM support library which provides
978 functional interfaces to some TPM commands.
979 Requires support for a TPM device.
981 CONFIG_TPM_AUTH_SESSIONS
982 Define this to enable authorized functions in the TPM library.
983 Requires CONFIG_TPM and CONFIG_SHA1.
985 - USB Support:
986 At the moment only the UHCI host controller is
987 supported (PIP405, MIP405); define
988 CONFIG_USB_UHCI to enable it.
989 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
990 and define CONFIG_USB_STORAGE to enable the USB
991 storage devices.
992 Note:
993 Supported are USB Keyboards and USB Floppy drives
994 (TEAC FD-05PUB).
996 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
997 txfilltuning field in the EHCI controller on reset.
999 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1000 HW module registers.
1002 - USB Device:
1003 Define the below if you wish to use the USB console.
1004 Once firmware is rebuilt from a serial console issue the
1005 command "setenv stdin usbtty; setenv stdout usbtty" and
1006 attach your USB cable. The Unix command "dmesg" should print
1007 it has found a new device. The environment variable usbtty
1008 can be set to gserial or cdc_acm to enable your device to
1009 appear to a USB host as a Linux gserial device or a
1010 Common Device Class Abstract Control Model serial device.
1011 If you select usbtty = gserial you should be able to enumerate
1012 a Linux host by
1013 # modprobe usbserial vendor=0xVendorID product=0xProductID
1014 else if using cdc_acm, simply setting the environment
1015 variable usbtty to be cdc_acm should suffice. The following
1016 might be defined in YourBoardName.h
1018 CONFIG_USB_DEVICE
1019 Define this to build a UDC device
1021 CONFIG_USB_TTY
1022 Define this to have a tty type of device available to
1023 talk to the UDC device
1025 CONFIG_USBD_HS
1026 Define this to enable the high speed support for usb
1027 device and usbtty. If this feature is enabled, a routine
1028 int is_usbd_high_speed(void)
1029 also needs to be defined by the driver to dynamically poll
1030 whether the enumeration has succeded at high speed or full
1031 speed.
1033 CONFIG_SYS_CONSOLE_IS_IN_ENV
1034 Define this if you want stdin, stdout &/or stderr to
1035 be set to usbtty.
1037 If you have a USB-IF assigned VendorID then you may wish to
1038 define your own vendor specific values either in BoardName.h
1039 or directly in usbd_vendor_info.h. If you don't define
1040 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1041 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1042 should pretend to be a Linux device to it's target host.
1044 CONFIG_USBD_MANUFACTURER
1045 Define this string as the name of your company for
1046 - CONFIG_USBD_MANUFACTURER "my company"
1048 CONFIG_USBD_PRODUCT_NAME
1049 Define this string as the name of your product
1050 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
1052 CONFIG_USBD_VENDORID
1053 Define this as your assigned Vendor ID from the USB
1054 Implementors Forum. This *must* be a genuine Vendor ID
1055 to avoid polluting the USB namespace.
1056 - CONFIG_USBD_VENDORID 0xFFFF
1058 CONFIG_USBD_PRODUCTID
1059 Define this as the unique Product ID
1060 for your device
1061 - CONFIG_USBD_PRODUCTID 0xFFFF
1063 - ULPI Layer Support:
1064 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1065 the generic ULPI layer. The generic layer accesses the ULPI PHY
1066 via the platform viewport, so you need both the genric layer and
1067 the viewport enabled. Currently only Chipidea/ARC based
1068 viewport is supported.
1069 To enable the ULPI layer support, define CONFIG_USB_ULPI and
1070 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1071 If your ULPI phy needs a different reference clock than the
1072 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1073 the appropriate value in Hz.
1075 - MMC Support:
1076 The MMC controller on the Intel PXA is supported. To
1077 enable this define CONFIG_MMC. The MMC can be
1078 accessed from the boot prompt by mapping the device
1079 to physical memory similar to flash. Command line is
1080 enabled with CONFIG_CMD_MMC. The MMC driver also works with
1081 the FAT fs. This is enabled with CONFIG_CMD_FAT.
1083 CONFIG_SH_MMCIF
1084 Support for Renesas on-chip MMCIF controller
1086 CONFIG_SH_MMCIF_ADDR
1087 Define the base address of MMCIF registers
1089 CONFIG_SH_MMCIF_CLK
1090 Define the clock frequency for MMCIF
1092 - USB Device Firmware Update (DFU) class support:
1093 CONFIG_DFU_OVER_USB
1094 This enables the USB portion of the DFU USB class
1096 CONFIG_DFU_NAND
1097 This enables support for exposing NAND devices via DFU.
1099 CONFIG_DFU_RAM
1100 This enables support for exposing RAM via DFU.
1101 Note: DFU spec refer to non-volatile memory usage, but
1102 allow usages beyond the scope of spec - here RAM usage,
1103 one that would help mostly the developer.
1105 CONFIG_SYS_DFU_DATA_BUF_SIZE
1106 Dfu transfer uses a buffer before writing data to the
1107 raw storage device. Make the size (in bytes) of this buffer
1108 configurable. The size of this buffer is also configurable
1109 through the "dfu_bufsiz" environment variable.
1111 CONFIG_SYS_DFU_MAX_FILE_SIZE
1112 When updating files rather than the raw storage device,
1113 we use a static buffer to copy the file into and then write
1114 the buffer once we've been given the whole file. Define
1115 this to the maximum filesize (in bytes) for the buffer.
1116 Default is 4 MiB if undefined.
1118 DFU_DEFAULT_POLL_TIMEOUT
1119 Poll timeout [ms], is the timeout a device can send to the
1120 host. The host must wait for this timeout before sending
1121 a subsequent DFU_GET_STATUS request to the device.
1123 DFU_MANIFEST_POLL_TIMEOUT
1124 Poll timeout [ms], which the device sends to the host when
1125 entering dfuMANIFEST state. Host waits this timeout, before
1126 sending again an USB request to the device.
1128 - Journaling Flash filesystem support:
1129 CONFIG_JFFS2_NAND
1130 Define these for a default partition on a NAND device
1132 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1133 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1134 Define these for a default partition on a NOR device
1136 - Keyboard Support:
1137 See Kconfig help for available keyboard drivers.
1139 CONFIG_KEYBOARD
1141 Define this to enable a custom keyboard support.
1142 This simply calls drv_keyboard_init() which must be
1143 defined in your board-specific files. This option is deprecated
1144 and is only used by novena. For new boards, use driver model
1145 instead.
1147 - Video support:
1148 CONFIG_FSL_DIU_FB
1149 Enable the Freescale DIU video driver. Reference boards for
1150 SOCs that have a DIU should define this macro to enable DIU
1151 support, and should also define these other macros:
1153 CONFIG_SYS_DIU_ADDR
1154 CONFIG_VIDEO
1155 CONFIG_CFB_CONSOLE
1156 CONFIG_VIDEO_SW_CURSOR
1157 CONFIG_VGA_AS_SINGLE_DEVICE
1158 CONFIG_VIDEO_LOGO
1159 CONFIG_VIDEO_BMP_LOGO
1161 The DIU driver will look for the 'video-mode' environment
1162 variable, and if defined, enable the DIU as a console during
1163 boot. See the documentation file doc/README.video for a
1164 description of this variable.
1166 - LCD Support: CONFIG_LCD
1168 Define this to enable LCD support (for output to LCD
1169 display); also select one of the supported displays
1170 by defining one of these:
1172 CONFIG_ATMEL_LCD:
1174 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1176 CONFIG_NEC_NL6448AC33:
1178 NEC NL6448AC33-18. Active, color, single scan.
1180 CONFIG_NEC_NL6448BC20
1182 NEC NL6448BC20-08. 6.5", 640x480.
1183 Active, color, single scan.
1185 CONFIG_NEC_NL6448BC33_54
1187 NEC NL6448BC33-54. 10.4", 640x480.
1188 Active, color, single scan.
1190 CONFIG_SHARP_16x9
1192 Sharp 320x240. Active, color, single scan.
1193 It isn't 16x9, and I am not sure what it is.
1195 CONFIG_SHARP_LQ64D341
1197 Sharp LQ64D341 display, 640x480.
1198 Active, color, single scan.
1200 CONFIG_HLD1045
1202 HLD1045 display, 640x480.
1203 Active, color, single scan.
1205 CONFIG_OPTREX_BW
1207 Optrex CBL50840-2 NF-FW 99 22 M5
1208 or
1209 Hitachi LMG6912RPFC-00T
1210 or
1211 Hitachi SP14Q002
1213 320x240. Black & white.
1215 CONFIG_LCD_ALIGNMENT
1217 Normally the LCD is page-aligned (typically 4KB). If this is
1218 defined then the LCD will be aligned to this value instead.
1219 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1220 here, since it is cheaper to change data cache settings on
1221 a per-section basis.
1224 CONFIG_LCD_ROTATION
1226 Sometimes, for example if the display is mounted in portrait
1227 mode or even if it's mounted landscape but rotated by 180degree,
1228 we need to rotate our content of the display relative to the
1229 framebuffer, so that user can read the messages which are
1230 printed out.
1231 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1232 initialized with a given rotation from "vl_rot" out of
1233 "vidinfo_t" which is provided by the board specific code.
1234 The value for vl_rot is coded as following (matching to
1235 fbcon=rotate:<n> linux-kernel commandline):
1236 0 = no rotation respectively 0 degree
1237 1 = 90 degree rotation
1238 2 = 180 degree rotation
1239 3 = 270 degree rotation
1241 If CONFIG_LCD_ROTATION is not defined, the console will be
1242 initialized with 0degree rotation.
1244 CONFIG_LCD_BMP_RLE8
1246 Support drawing of RLE8-compressed bitmaps on the LCD.
1248 CONFIG_I2C_EDID
1250 Enables an 'i2c edid' command which can read EDID
1251 information over I2C from an attached LCD display.
1253 - MII/PHY support:
1254 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1256 The clock frequency of the MII bus
1258 CONFIG_PHY_RESET_DELAY
1260 Some PHY like Intel LXT971A need extra delay after
1261 reset before any MII register access is possible.
1262 For such PHY, set this option to the usec delay
1263 required. (minimum 300usec for LXT971A)
1265 CONFIG_PHY_CMD_DELAY (ppc4xx)
1267 Some PHY like Intel LXT971A need extra delay after
1268 command issued before MII status register can be read
1270 - IP address:
1271 CONFIG_IPADDR
1273 Define a default value for the IP address to use for
1274 the default Ethernet interface, in case this is not
1275 determined through e.g. bootp.
1276 (Environment variable "ipaddr")
1278 - Server IP address:
1279 CONFIG_SERVERIP
1281 Defines a default value for the IP address of a TFTP
1282 server to contact when using the "tftboot" command.
1283 (Environment variable "serverip")
1285 CONFIG_KEEP_SERVERADDR
1287 Keeps the server's MAC address, in the env 'serveraddr'
1288 for passing to bootargs (like Linux's netconsole option)
1290 - Gateway IP address:
1291 CONFIG_GATEWAYIP
1293 Defines a default value for the IP address of the
1294 default router where packets to other networks are
1295 sent to.
1296 (Environment variable "gatewayip")
1298 - Subnet mask:
1299 CONFIG_NETMASK
1301 Defines a default value for the subnet mask (or
1302 routing prefix) which is used to determine if an IP
1303 address belongs to the local subnet or needs to be
1304 forwarded through a router.
1305 (Environment variable "netmask")
1307 - BOOTP Recovery Mode:
1308 CONFIG_BOOTP_RANDOM_DELAY
1310 If you have many targets in a network that try to
1311 boot using BOOTP, you may want to avoid that all
1312 systems send out BOOTP requests at precisely the same
1313 moment (which would happen for instance at recovery
1314 from a power failure, when all systems will try to
1315 boot, thus flooding the BOOTP server. Defining
1316 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1317 inserted before sending out BOOTP requests. The
1318 following delays are inserted then:
1320 1st BOOTP request: delay 0 ... 1 sec
1321 2nd BOOTP request: delay 0 ... 2 sec
1322 3rd BOOTP request: delay 0 ... 4 sec
1323 4th and following
1324 BOOTP requests: delay 0 ... 8 sec
1326 CONFIG_BOOTP_ID_CACHE_SIZE
1328 BOOTP packets are uniquely identified using a 32-bit ID. The
1329 server will copy the ID from client requests to responses and
1330 U-Boot will use this to determine if it is the destination of
1331 an incoming response. Some servers will check that addresses
1332 aren't in use before handing them out (usually using an ARP
1333 ping) and therefore take up to a few hundred milliseconds to
1334 respond. Network congestion may also influence the time it
1335 takes for a response to make it back to the client. If that
1336 time is too long, U-Boot will retransmit requests. In order
1337 to allow earlier responses to still be accepted after these
1338 retransmissions, U-Boot's BOOTP client keeps a small cache of
1339 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1340 cache. The default is to keep IDs for up to four outstanding
1341 requests. Increasing this will allow U-Boot to accept offers
1342 from a BOOTP client in networks with unusually high latency.
1344 - DHCP Advanced Options:
1345 You can fine tune the DHCP functionality by defining
1346 CONFIG_BOOTP_* symbols:
1348 CONFIG_BOOTP_NISDOMAIN
1349 CONFIG_BOOTP_BOOTFILESIZE
1350 CONFIG_BOOTP_NTPSERVER
1351 CONFIG_BOOTP_TIMEOFFSET
1352 CONFIG_BOOTP_VENDOREX
1353 CONFIG_BOOTP_MAY_FAIL
1355 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1356 environment variable, not the BOOTP server.
1358 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1359 after the configured retry count, the call will fail
1360 instead of starting over. This can be used to fail over
1361 to Link-local IP address configuration if the DHCP server
1362 is not available.
1364 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1366 A 32bit value in microseconds for a delay between
1367 receiving a "DHCP Offer" and sending the "DHCP Request".
1368 This fixes a problem with certain DHCP servers that don't
1369 respond 100% of the time to a "DHCP request". E.g. On an
1370 AT91RM9200 processor running at 180MHz, this delay needed
1371 to be *at least* 15,000 usec before a Windows Server 2003
1372 DHCP server would reply 100% of the time. I recommend at
1373 least 50,000 usec to be safe. The alternative is to hope
1374 that one of the retries will be successful but note that
1375 the DHCP timeout and retry process takes a longer than
1376 this delay.
1378 - Link-local IP address negotiation:
1379 Negotiate with other link-local clients on the local network
1380 for an address that doesn't require explicit configuration.
1381 This is especially useful if a DHCP server cannot be guaranteed
1382 to exist in all environments that the device must operate.
1384 See doc/README.link-local for more information.
1386 - MAC address from environment variables
1388 FDT_SEQ_MACADDR_FROM_ENV
1390 Fix-up device tree with MAC addresses fetched sequentially from
1391 environment variables. This config work on assumption that
1392 non-usable ethernet node of device-tree are either not present
1393 or their status has been marked as "disabled".
1395 - CDP Options:
1396 CONFIG_CDP_DEVICE_ID
1398 The device id used in CDP trigger frames.
1400 CONFIG_CDP_DEVICE_ID_PREFIX
1402 A two character string which is prefixed to the MAC address
1403 of the device.
1405 CONFIG_CDP_PORT_ID
1407 A printf format string which contains the ascii name of
1408 the port. Normally is set to "eth%d" which sets
1409 eth0 for the first Ethernet, eth1 for the second etc.
1411 CONFIG_CDP_CAPABILITIES
1413 A 32bit integer which indicates the device capabilities;
1414 0x00000010 for a normal host which does not forwards.
1416 CONFIG_CDP_VERSION
1418 An ascii string containing the version of the software.
1420 CONFIG_CDP_PLATFORM
1422 An ascii string containing the name of the platform.
1424 CONFIG_CDP_TRIGGER
1426 A 32bit integer sent on the trigger.
1428 CONFIG_CDP_POWER_CONSUMPTION
1430 A 16bit integer containing the power consumption of the
1431 device in .1 of milliwatts.
1433 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1435 A byte containing the id of the VLAN.
1437 - Status LED: CONFIG_LED_STATUS
1439 Several configurations allow to display the current
1440 status using a LED. For instance, the LED will blink
1441 fast while running U-Boot code, stop blinking as
1442 soon as a reply to a BOOTP request was received, and
1443 start blinking slow once the Linux kernel is running
1444 (supported by a status LED driver in the Linux
1445 kernel). Defining CONFIG_LED_STATUS enables this
1446 feature in U-Boot.
1448 Additional options:
1450 CONFIG_LED_STATUS_GPIO
1451 The status LED can be connected to a GPIO pin.
1452 In such cases, the gpio_led driver can be used as a
1453 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1454 to include the gpio_led driver in the U-Boot binary.
1456 CONFIG_GPIO_LED_INVERTED_TABLE
1457 Some GPIO connected LEDs may have inverted polarity in which
1458 case the GPIO high value corresponds to LED off state and
1459 GPIO low value corresponds to LED on state.
1460 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1461 with a list of GPIO LEDs that have inverted polarity.
1463 - I2C Support: CONFIG_SYS_I2C
1465 This enable the NEW i2c subsystem, and will allow you to use
1466 i2c commands at the u-boot command line (as long as you set
1467 CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
1468 for defining speed and slave address
1469 - activate second bus with I2C_SOFT_DECLARATIONS2 define
1470 CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
1471 for defining speed and slave address
1472 - activate third bus with I2C_SOFT_DECLARATIONS3 define
1473 CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
1474 for defining speed and slave address
1475 - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
1476 CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
1477 for defining speed and slave address
1479 - drivers/i2c/fsl_i2c.c:
1480 - activate i2c driver with CONFIG_SYS_I2C_FSL
1481 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1482 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1483 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1484 bus.
1485 - If your board supports a second fsl i2c bus, define
1486 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1487 CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1488 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
1489 second bus.
1491 - drivers/i2c/tegra_i2c.c:
1492 - activate this driver with CONFIG_SYS_I2C_TEGRA
1493 - This driver adds 4 i2c buses with a fix speed from
1494 100000 and the slave addr 0!
1496 - drivers/i2c/ppc4xx_i2c.c
1497 - activate this driver with CONFIG_SYS_I2C_PPC4XX
1498 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
1499 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
1501 - drivers/i2c/i2c_mxc.c
1502 - activate this driver with CONFIG_SYS_I2C_MXC
1503 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
1504 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
1505 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
1506 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
1507 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
1508 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
1509 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
1510 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
1511 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
1512 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
1513 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
1514 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
1515 If those defines are not set, default value is 100000
1516 for speed, and 0 for slave.
1518 - drivers/i2c/rcar_i2c.c:
1519 - activate this driver with CONFIG_SYS_I2C_RCAR
1520 - This driver adds 4 i2c buses
1522 - drivers/i2c/sh_i2c.c:
1523 - activate this driver with CONFIG_SYS_I2C_SH
1524 - This driver adds from 2 to 5 i2c buses
1526 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
1527 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
1528 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
1529 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
1530 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
1531 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
1532 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
1533 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
1534 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
1535 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
1536 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
1538 - drivers/i2c/omap24xx_i2c.c
1539 - activate this driver with CONFIG_SYS_I2C_OMAP24XX
1540 - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
1541 - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
1542 - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
1543 - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
1544 - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
1545 - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
1546 - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
1547 - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
1548 - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
1549 - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
1551 - drivers/i2c/s3c24x0_i2c.c:
1552 - activate this driver with CONFIG_SYS_I2C_S3C24X0
1553 - This driver adds i2c buses (11 for Exynos5250, Exynos5420
1554 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
1555 with a fix speed from 100000 and the slave addr 0!
1557 - drivers/i2c/ihs_i2c.c
1558 - activate this driver with CONFIG_SYS_I2C_IHS
1559 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
1560 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
1561 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
1562 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
1563 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
1564 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
1565 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
1566 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
1567 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
1568 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
1569 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
1570 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
1571 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
1572 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
1573 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
1574 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
1575 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
1576 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
1577 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
1578 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
1579 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
1581 additional defines:
1583 CONFIG_SYS_NUM_I2C_BUSES
1584 Hold the number of i2c buses you want to use.
1586 CONFIG_SYS_I2C_DIRECT_BUS
1587 define this, if you don't use i2c muxes on your hardware.
1588 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1589 omit this define.
1591 CONFIG_SYS_I2C_MAX_HOPS
1592 define how many muxes are maximal consecutively connected
1593 on one i2c bus. If you not use i2c muxes, omit this
1594 define.
1596 CONFIG_SYS_I2C_BUSES
1597 hold a list of buses you want to use, only used if
1598 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1599 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1600 CONFIG_SYS_NUM_I2C_BUSES = 9:
1602 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1603 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1604 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1605 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1606 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1607 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1608 {1, {I2C_NULL_HOP}}, \
1609 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1610 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1611 }
1613 which defines
1614 bus 0 on adapter 0 without a mux
1615 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1616 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1617 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1618 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1619 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1620 bus 6 on adapter 1 without a mux
1621 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1622 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1624 If you do not have i2c muxes on your board, omit this define.
1626 - Legacy I2C Support:
1627 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1628 then the following macros need to be defined (examples are
1629 from include/configs/lwmon.h):
1631 I2C_INIT
1633 (Optional). Any commands necessary to enable the I2C
1634 controller or configure ports.
1636 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1638 I2C_ACTIVE
1640 The code necessary to make the I2C data line active
1641 (driven). If the data line is open collector, this
1642 define can be null.
1644 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1646 I2C_TRISTATE
1648 The code necessary to make the I2C data line tri-stated
1649 (inactive). If the data line is open collector, this
1650 define can be null.
1652 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1654 I2C_READ
1656 Code that returns true if the I2C data line is high,
1657 false if it is low.
1659 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1661 I2C_SDA(bit)
1663 If <bit> is true, sets the I2C data line high. If it
1664 is false, it clears it (low).
1666 eg: #define I2C_SDA(bit) \
1667 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1668 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1670 I2C_SCL(bit)
1672 If <bit> is true, sets the I2C clock line high. If it
1673 is false, it clears it (low).
1675 eg: #define I2C_SCL(bit) \
1676 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1677 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1679 I2C_DELAY
1681 This delay is invoked four times per clock cycle so this
1682 controls the rate of data transfer. The data rate thus
1683 is 1 / (I2C_DELAY * 4). Often defined to be something
1684 like:
1686 #define I2C_DELAY udelay(2)
1688 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1690 If your arch supports the generic GPIO framework (asm/gpio.h),
1691 then you may alternatively define the two GPIOs that are to be
1692 used as SCL / SDA. Any of the previous I2C_xxx macros will
1693 have GPIO-based defaults assigned to them as appropriate.
1695 You should define these to the GPIO value as given directly to
1696 the generic GPIO functions.
1698 CONFIG_SYS_I2C_INIT_BOARD
1700 When a board is reset during an i2c bus transfer
1701 chips might think that the current transfer is still
1702 in progress. On some boards it is possible to access
1703 the i2c SCLK line directly, either by using the
1704 processor pin as a GPIO or by having a second pin
1705 connected to the bus. If this option is defined a
1706 custom i2c_init_board() routine in boards/xxx/board.c
1707 is run early in the boot sequence.
1709 CONFIG_I2C_MULTI_BUS
1711 This option allows the use of multiple I2C buses, each of which
1712 must have a controller. At any point in time, only one bus is
1713 active. To switch to a different bus, use the 'i2c dev' command.
1714 Note that bus numbering is zero-based.
1716 CONFIG_SYS_I2C_NOPROBES
1718 This option specifies a list of I2C devices that will be skipped
1719 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1720 is set, specify a list of bus-device pairs. Otherwise, specify
1721 a 1D array of device addresses
1723 e.g.
1724 #undef CONFIG_I2C_MULTI_BUS
1725 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1727 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1729 #define CONFIG_I2C_MULTI_BUS
1730 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1732 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1734 CONFIG_SYS_SPD_BUS_NUM
1736 If defined, then this indicates the I2C bus number for DDR SPD.
1737 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1739 CONFIG_SYS_RTC_BUS_NUM
1741 If defined, then this indicates the I2C bus number for the RTC.
1742 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1744 CONFIG_SOFT_I2C_READ_REPEATED_START
1746 defining this will force the i2c_read() function in
1747 the soft_i2c driver to perform an I2C repeated start
1748 between writing the address pointer and reading the
1749 data. If this define is omitted the default behaviour
1750 of doing a stop-start sequence will be used. Most I2C
1751 devices can use either method, but some require one or
1752 the other.
1754 - SPI Support: CONFIG_SPI
1756 Enables SPI driver (so far only tested with
1757 SPI EEPROM, also an instance works with Crystal A/D and
1758 D/As on the SACSng board)
1760 CONFIG_SOFT_SPI
1762 Enables a software (bit-bang) SPI driver rather than
1763 using hardware support. This is a general purpose
1764 driver that only requires three general I/O port pins
1765 (two outputs, one input) to function. If this is
1766 defined, the board configuration must define several
1767 SPI configuration items (port pins to use, etc). For
1768 an example, see include/configs/sacsng.h.
1770 CONFIG_SYS_SPI_MXC_WAIT
1771 Timeout for waiting until spi transfer completed.
1772 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1774 - FPGA Support: CONFIG_FPGA
1776 Enables FPGA subsystem.
1778 CONFIG_FPGA_<vendor>
1780 Enables support for specific chip vendors.
1781 (ALTERA, XILINX)
1783 CONFIG_FPGA_<family>
1785 Enables support for FPGA family.
1786 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1788 CONFIG_FPGA_COUNT
1790 Specify the number of FPGA devices to support.
1792 CONFIG_SYS_FPGA_PROG_FEEDBACK
1794 Enable printing of hash marks during FPGA configuration.
1796 CONFIG_SYS_FPGA_CHECK_BUSY
1798 Enable checks on FPGA configuration interface busy
1799 status by the configuration function. This option
1800 will require a board or device specific function to
1801 be written.
1803 CONFIG_FPGA_DELAY
1805 If defined, a function that provides delays in the FPGA
1806 configuration driver.
1808 CONFIG_SYS_FPGA_CHECK_CTRLC
1809 Allow Control-C to interrupt FPGA configuration
1811 CONFIG_SYS_FPGA_CHECK_ERROR
1813 Check for configuration errors during FPGA bitfile
1814 loading. For example, abort during Virtex II
1815 configuration if the INIT_B line goes low (which
1816 indicated a CRC error).
1818 CONFIG_SYS_FPGA_WAIT_INIT
1820 Maximum time to wait for the INIT_B line to de-assert
1821 after PROB_B has been de-asserted during a Virtex II
1822 FPGA configuration sequence. The default time is 500
1823 ms.
1825 CONFIG_SYS_FPGA_WAIT_BUSY
1827 Maximum time to wait for BUSY to de-assert during
1828 Virtex II FPGA configuration. The default is 5 ms.
1830 CONFIG_SYS_FPGA_WAIT_CONFIG
1832 Time to wait after FPGA configuration. The default is
1833 200 ms.
1835 - Configuration Management:
1837 CONFIG_IDENT_STRING
1839 If defined, this string will be added to the U-Boot
1840 version information (U_BOOT_VERSION)
1842 - Vendor Parameter Protection:
1844 U-Boot considers the values of the environment
1845 variables "serial#" (Board Serial Number) and
1846 "ethaddr" (Ethernet Address) to be parameters that
1847 are set once by the board vendor / manufacturer, and
1848 protects these variables from casual modification by
1849 the user. Once set, these variables are read-only,
1850 and write or delete attempts are rejected. You can
1851 change this behaviour:
1853 If CONFIG_ENV_OVERWRITE is #defined in your config
1854 file, the write protection for vendor parameters is
1855 completely disabled. Anybody can change or delete
1856 these parameters.
1858 Alternatively, if you define _both_ an ethaddr in the
1859 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1860 Ethernet address is installed in the environment,
1861 which can be changed exactly ONCE by the user. [The
1862 serial# is unaffected by this, i. e. it remains
1863 read-only.]
1865 The same can be accomplished in a more flexible way
1866 for any variable by configuring the type of access
1867 to allow for those variables in the ".flags" variable
1868 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1870 - Protected RAM:
1871 CONFIG_PRAM
1873 Define this variable to enable the reservation of
1874 "protected RAM", i. e. RAM which is not overwritten
1875 by U-Boot. Define CONFIG_PRAM to hold the number of
1876 kB you want to reserve for pRAM. You can overwrite
1877 this default value by defining an environment
1878 variable "pram" to the number of kB you want to
1879 reserve. Note that the board info structure will
1880 still show the full amount of RAM. If pRAM is
1881 reserved, a new environment variable "mem" will
1882 automatically be defined to hold the amount of
1883 remaining RAM in a form that can be passed as boot
1884 argument to Linux, for instance like that:
1886 setenv bootargs ... mem=\${mem}
1887 saveenv
1889 This way you can tell Linux not to use this memory,
1890 either, which results in a memory region that will
1891 not be affected by reboots.
1893 *WARNING* If your board configuration uses automatic
1894 detection of the RAM size, you must make sure that
1895 this memory test is non-destructive. So far, the
1896 following board configurations are known to be
1897 "pRAM-clean":
1899 IVMS8, IVML24, SPD8xx,
1900 HERMES, IP860, RPXlite, LWMON,
1901 FLAGADM
1903 - Access to physical memory region (> 4GB)
1904 Some basic support is provided for operations on memory not
1905 normally accessible to U-Boot - e.g. some architectures
1906 support access to more than 4GB of memory on 32-bit
1907 machines using physical address extension or similar.
1908 Define CONFIG_PHYSMEM to access this basic support, which
1909 currently only supports clearing the memory.
1911 - Error Recovery:
1912 CONFIG_NET_RETRY_COUNT
1914 This variable defines the number of retries for
1915 network operations like ARP, RARP, TFTP, or BOOTP
1916 before giving up the operation. If not defined, a
1917 default value of 5 is used.
1919 CONFIG_ARP_TIMEOUT
1921 Timeout waiting for an ARP reply in milliseconds.
1923 CONFIG_NFS_TIMEOUT
1925 Timeout in milliseconds used in NFS protocol.
1926 If you encounter "ERROR: Cannot umount" in nfs command,
1927 try longer timeout such as
1928 #define CONFIG_NFS_TIMEOUT 10000UL
1930 - Command Interpreter:
1931 CONFIG_SYS_PROMPT_HUSH_PS2
1933 This defines the secondary prompt string, which is
1934 printed when the command interpreter needs more input
1935 to complete a command. Usually "> ".
1937 Note:
1939 In the current implementation, the local variables
1940 space and global environment variables space are
1941 separated. Local variables are those you define by
1942 simply typing `name=value'. To access a local
1943 variable later on, you have write `$name' or
1944 `${name}'; to execute the contents of a variable
1945 directly type `$name' at the command prompt.
1947 Global environment variables are those you use
1948 setenv/printenv to work with. To run a command stored
1949 in such a variable, you need to use the run command,
1950 and you must not use the '$' sign to access them.
1952 To store commands and special characters in a
1953 variable, please use double quotation marks
1954 surrounding the whole text of the variable, instead
1955 of the backslashes before semicolons and special
1956 symbols.
1958 - Command Line Editing and History:
1959 CONFIG_CMDLINE_PS_SUPPORT
1961 Enable support for changing the command prompt string
1962 at run-time. Only static string is supported so far.
1963 The string is obtained from environment variables PS1
1964 and PS2.
1966 - Default Environment:
1967 CONFIG_EXTRA_ENV_SETTINGS
1969 Define this to contain any number of null terminated
1970 strings (variable = value pairs) that will be part of
1971 the default environment compiled into the boot image.
1973 For example, place something like this in your
1974 board's config file:
1976 #define CONFIG_EXTRA_ENV_SETTINGS \
1977 "myvar1=value1\0" \
1978 "myvar2=value2\0"
1980 Warning: This method is based on knowledge about the
1981 internal format how the environment is stored by the
1982 U-Boot code. This is NOT an official, exported
1983 interface! Although it is unlikely that this format
1984 will change soon, there is no guarantee either.
1985 You better know what you are doing here.
1987 Note: overly (ab)use of the default environment is
1988 discouraged. Make sure to check other ways to preset
1989 the environment like the "source" command or the
1990 boot command first.
1992 CONFIG_DELAY_ENVIRONMENT
1994 Normally the environment is loaded when the board is
1995 initialised so that it is available to U-Boot. This inhibits
1996 that so that the environment is not available until
1997 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1998 this is instead controlled by the value of
1999 /config/load-environment.
2001 - TFTP Fixed UDP Port:
2002 CONFIG_TFTP_PORT
2004 If this is defined, the environment variable tftpsrcp
2005 is used to supply the TFTP UDP source port value.
2006 If tftpsrcp isn't defined, the normal pseudo-random port
2007 number generator is used.
2009 Also, the environment variable tftpdstp is used to supply
2010 the TFTP UDP destination port value. If tftpdstp isn't
2011 defined, the normal port 69 is used.
2013 The purpose for tftpsrcp is to allow a TFTP server to
2014 blindly start the TFTP transfer using the pre-configured
2015 target IP address and UDP port. This has the effect of
2016 "punching through" the (Windows XP) firewall, allowing
2017 the remainder of the TFTP transfer to proceed normally.
2018 A better solution is to properly configure the firewall,
2019 but sometimes that is not allowed.
2021 CONFIG_STANDALONE_LOAD_ADDR
2023 This option defines a board specific value for the
2024 address where standalone program gets loaded, thus
2025 overwriting the architecture dependent default
2026 settings.
2028 - Frame Buffer Address:
2029 CONFIG_FB_ADDR
2031 Define CONFIG_FB_ADDR if you want to use specific
2032 address for frame buffer. This is typically the case
2033 when using a graphics controller has separate video
2034 memory. U-Boot will then place the frame buffer at
2035 the given address instead of dynamically reserving it
2036 in system RAM by calling lcd_setmem(), which grabs
2037 the memory for the frame buffer depending on the
2038 configured panel size.
2040 Please see board_init_f function.
2042 - Automatic software updates via TFTP server
2043 CONFIG_UPDATE_TFTP
2044 CONFIG_UPDATE_TFTP_CNT_MAX
2045 CONFIG_UPDATE_TFTP_MSEC_MAX
2047 These options enable and control the auto-update feature;
2048 for a more detailed description refer to doc/README.update.
2050 - MTD Support (mtdparts command, UBI support)
2051 CONFIG_MTD_UBI_WL_THRESHOLD
2052 This parameter defines the maximum difference between the highest
2053 erase counter value and the lowest erase counter value of eraseblocks
2054 of UBI devices. When this threshold is exceeded, UBI starts performing
2055 wear leveling by means of moving data from eraseblock with low erase
2056 counter to eraseblocks with high erase counter.
2058 The default value should be OK for SLC NAND flashes, NOR flashes and
2059 other flashes which have eraseblock life-cycle 100000 or more.
2060 However, in case of MLC NAND flashes which typically have eraseblock
2061 life-cycle less than 10000, the threshold should be lessened (e.g.,
2062 to 128 or 256, although it does not have to be power of 2).
2064 default: 4096
2066 CONFIG_MTD_UBI_BEB_LIMIT
2067 This option specifies the maximum bad physical eraseblocks UBI
2068 expects on the MTD device (per 1024 eraseblocks). If the
2069 underlying flash does not admit of bad eraseblocks (e.g. NOR
2070 flash), this value is ignored.
2072 NAND datasheets often specify the minimum and maximum NVM
2073 (Number of Valid Blocks) for the flashes' endurance lifetime.
2074 The maximum expected bad eraseblocks per 1024 eraseblocks
2075 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
2076 which gives 20 for most NANDs (MaxNVB is basically the total
2077 count of eraseblocks on the chip).
2079 To put it differently, if this value is 20, UBI will try to
2080 reserve about 1.9% of physical eraseblocks for bad blocks
2081 handling. And that will be 1.9% of eraseblocks on the entire
2082 NAND chip, not just the MTD partition UBI attaches. This means
2083 that if you have, say, a NAND flash chip admits maximum 40 bad
2084 eraseblocks, and it is split on two MTD partitions of the same
2085 size, UBI will reserve 40 eraseblocks when attaching a
2086 partition.
2088 default: 20
2090 CONFIG_MTD_UBI_FASTMAP
2091 Fastmap is a mechanism which allows attaching an UBI device
2092 in nearly constant time. Instead of scanning the whole MTD device it
2093 only has to locate a checkpoint (called fastmap) on the device.
2094 The on-flash fastmap contains all information needed to attach
2095 the device. Using fastmap makes only sense on large devices where
2096 attaching by scanning takes long. UBI will not automatically install
2097 a fastmap on old images, but you can set the UBI parameter
2098 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
2099 that fastmap-enabled images are still usable with UBI implementations
2100 without fastmap support. On typical flash devices the whole fastmap
2101 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
2103 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
2104 Set this parameter to enable fastmap automatically on images
2105 without a fastmap.
2106 default: 0
2108 CONFIG_MTD_UBI_FM_DEBUG
2109 Enable UBI fastmap debug
2110 default: 0
2112 - SPL framework
2113 CONFIG_SPL
2114 Enable building of SPL globally.
2116 CONFIG_SPL_LDSCRIPT
2117 LDSCRIPT for linking the SPL binary.
2119 CONFIG_SPL_MAX_FOOTPRINT
2120 Maximum size in memory allocated to the SPL, BSS included.
2121 When defined, the linker checks that the actual memory
2122 used by SPL from _start to __bss_end does not exceed it.
2123 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2124 must not be both defined at the same time.
2126 CONFIG_SPL_MAX_SIZE
2127 Maximum size of the SPL image (text, data, rodata, and
2128 linker lists sections), BSS excluded.
2129 When defined, the linker checks that the actual size does
2130 not exceed it.
2132 CONFIG_SPL_RELOC_TEXT_BASE
2133 Address to relocate to. If unspecified, this is equal to
2134 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2136 CONFIG_SPL_BSS_START_ADDR
2137 Link address for the BSS within the SPL binary.
2139 CONFIG_SPL_BSS_MAX_SIZE
2140 Maximum size in memory allocated to the SPL BSS.
2141 When defined, the linker checks that the actual memory used
2142 by SPL from __bss_start to __bss_end does not exceed it.
2143 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2144 must not be both defined at the same time.
2146 CONFIG_SPL_STACK
2147 Adress of the start of the stack SPL will use
2149 CONFIG_SPL_PANIC_ON_RAW_IMAGE
2150 When defined, SPL will panic() if the image it has
2151 loaded does not have a signature.
2152 Defining this is useful when code which loads images
2153 in SPL cannot guarantee that absolutely all read errors
2154 will be caught.
2155 An example is the LPC32XX MLC NAND driver, which will
2156 consider that a completely unreadable NAND block is bad,
2157 and thus should be skipped silently.
2159 CONFIG_SPL_RELOC_STACK
2160 Adress of the start of the stack SPL will use after
2161 relocation. If unspecified, this is equal to
2162 CONFIG_SPL_STACK.
2164 CONFIG_SYS_SPL_MALLOC_START
2165 Starting address of the malloc pool used in SPL.
2166 When this option is set the full malloc is used in SPL and
2167 it is set up by spl_init() and before that, the simple malloc()
2168 can be used if CONFIG_SYS_MALLOC_F is defined.
2170 CONFIG_SYS_SPL_MALLOC_SIZE
2171 The size of the malloc pool used in SPL.
2173 CONFIG_SPL_OS_BOOT
2174 Enable booting directly to an OS from SPL.
2175 See also: doc/README.falcon
2177 CONFIG_SPL_DISPLAY_PRINT
2178 For ARM, enable an optional function to print more information
2179 about the running system.
2181 CONFIG_SPL_INIT_MINIMAL
2182 Arch init code should be built for a very small image
2184 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2185 Partition on the MMC to load U-Boot from when the MMC is being
2186 used in raw mode
2188 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2189 Sector to load kernel uImage from when MMC is being
2190 used in raw mode (for Falcon mode)
2192 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2193 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2194 Sector and number of sectors to load kernel argument
2195 parameters from when MMC is being used in raw mode
2196 (for falcon mode)
2198 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2199 Filename to read to load U-Boot when reading from filesystem
2201 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2202 Filename to read to load kernel uImage when reading
2203 from filesystem (for Falcon mode)
2205 CONFIG_SPL_FS_LOAD_ARGS_NAME
2206 Filename to read to load kernel argument parameters
2207 when reading from filesystem (for Falcon mode)
2209 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2210 Set this for NAND SPL on PPC mpc83xx targets, so that
2211 start.S waits for the rest of the SPL to load before
2212 continuing (the hardware starts execution after just
2213 loading the first page rather than the full 4K).
2215 CONFIG_SPL_SKIP_RELOCATE
2216 Avoid SPL relocation
2218 CONFIG_SPL_NAND_IDENT
2219 SPL uses the chip ID list to identify the NAND flash.
2220 Requires CONFIG_SPL_NAND_BASE.
2222 CONFIG_SPL_UBI
2223 Support for a lightweight UBI (fastmap) scanner and
2224 loader
2226 CONFIG_SPL_NAND_RAW_ONLY
2227 Support to boot only raw u-boot.bin images. Use this only
2228 if you need to save space.
2230 CONFIG_SPL_COMMON_INIT_DDR
2231 Set for common ddr init with serial presence detect in
2232 SPL binary.
2234 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2235 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2236 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2237 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2238 CONFIG_SYS_NAND_ECCBYTES
2239 Defines the size and behavior of the NAND that SPL uses
2240 to read U-Boot
2242 CONFIG_SYS_NAND_U_BOOT_OFFS
2243 Location in NAND to read U-Boot from
2245 CONFIG_SYS_NAND_U_BOOT_DST
2246 Location in memory to load U-Boot to
2248 CONFIG_SYS_NAND_U_BOOT_SIZE
2249 Size of image to load
2251 CONFIG_SYS_NAND_U_BOOT_START
2252 Entry point in loaded image to jump to
2254 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2255 Define this if you need to first read the OOB and then the
2256 data. This is used, for example, on davinci platforms.
2258 CONFIG_SPL_RAM_DEVICE
2259 Support for running image already present in ram, in SPL binary
2261 CONFIG_SPL_PAD_TO
2262 Image offset to which the SPL should be padded before appending
2263 the SPL payload. By default, this is defined as
2264 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2265 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2266 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2268 CONFIG_SPL_TARGET
2269 Final target image containing SPL and payload. Some SPLs
2270 use an arch-specific makefile fragment instead, for
2271 example if more than one image needs to be produced.
2273 CONFIG_SPL_FIT_PRINT
2274 Printing information about a FIT image adds quite a bit of
2275 code to SPL. So this is normally disabled in SPL. Use this
2276 option to re-enable it. This will affect the output of the
2277 bootm command when booting a FIT image.
2279 - TPL framework
2280 CONFIG_TPL
2281 Enable building of TPL globally.
2283 CONFIG_TPL_PAD_TO
2284 Image offset to which the TPL should be padded before appending
2285 the TPL payload. By default, this is defined as
2286 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2287 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2288 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2290 - Interrupt support (PPC):
2292 There are common interrupt_init() and timer_interrupt()
2293 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2294 for CPU specific initialization. interrupt_init_cpu()
2295 should set decrementer_count to appropriate value. If
2296 CPU resets decrementer automatically after interrupt
2297 (ppc4xx) it should set decrementer_count to zero.
2298 timer_interrupt() calls timer_interrupt_cpu() for CPU
2299 specific handling. If board has watchdog / status_led
2300 / other_activity_monitor it works automatically from
2301 general timer_interrupt().
2304 Board initialization settings:
2305 ------------------------------
2307 During Initialization u-boot calls a number of board specific functions
2308 to allow the preparation of board specific prerequisites, e.g. pin setup
2309 before drivers are initialized. To enable these callbacks the
2310 following configuration macros have to be defined. Currently this is
2311 architecture specific, so please check arch/your_architecture/lib/board.c
2312 typically in board_init_f() and board_init_r().
2314 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2315 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2316 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2317 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2319 Configuration Settings:
2320 -----------------------
2322 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2323 Optionally it can be defined to support 64-bit memory commands.
2325 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2326 undefine this when you're short of memory.
2328 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2329 width of the commands listed in the 'help' command output.
2331 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2332 prompt for user input.
2334 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2336 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2338 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2340 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2341 the application (usually a Linux kernel) when it is
2342 booted
2344 - CONFIG_SYS_BAUDRATE_TABLE:
2345 List of legal baudrate settings for this board.
2347 - CONFIG_SYS_MEM_RESERVE_SECURE
2348 Only implemented for ARMv8 for now.
2349 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2350 is substracted from total RAM and won't be reported to OS.
2351 This memory can be used as secure memory. A variable
2352 gd->arch.secure_ram is used to track the location. In systems
2353 the RAM base is not zero, or RAM is divided into banks,
2354 this variable needs to be recalcuated to get the address.
2356 - CONFIG_SYS_MEM_TOP_HIDE:
2357 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2358 this specified memory area will get subtracted from the top
2359 (end) of RAM and won't get "touched" at all by U-Boot. By
2360 fixing up gd->ram_size the Linux kernel should gets passed
2361 the now "corrected" memory size and won't touch it either.
2362 This should work for arch/ppc and arch/powerpc. Only Linux
2363 board ports in arch/powerpc with bootwrapper support that
2364 recalculate the memory size from the SDRAM controller setup
2365 will have to get fixed in Linux additionally.
2367 This option can be used as a workaround for the 440EPx/GRx
2368 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2369 be touched.
2371 WARNING: Please make sure that this value is a multiple of
2372 the Linux page size (normally 4k). If this is not the case,
2373 then the end address of the Linux memory will be located at a
2374 non page size aligned address and this could cause major
2375 problems.
2377 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2378 Enable temporary baudrate change while serial download
2380 - CONFIG_SYS_SDRAM_BASE:
2381 Physical start address of SDRAM. _Must_ be 0 here.
2383 - CONFIG_SYS_FLASH_BASE:
2384 Physical start address of Flash memory.
2386 - CONFIG_SYS_MONITOR_BASE:
2387 Physical start address of boot monitor code (set by
2388 make config files to be same as the text base address
2389 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2390 CONFIG_SYS_FLASH_BASE when booting from flash.
2392 - CONFIG_SYS_MONITOR_LEN:
2393 Size of memory reserved for monitor code, used to
2394 determine _at_compile_time_ (!) if the environment is
2395 embedded within the U-Boot image, or in a separate
2396 flash sector.
2398 - CONFIG_SYS_MALLOC_LEN:
2399 Size of DRAM reserved for malloc() use.
2401 - CONFIG_SYS_MALLOC_F_LEN
2402 Size of the malloc() pool for use before relocation. If
2403 this is defined, then a very simple malloc() implementation
2404 will become available before relocation. The address is just
2405 below the global data, and the stack is moved down to make
2406 space.
2408 This feature allocates regions with increasing addresses
2409 within the region. calloc() is supported, but realloc()
2410 is not available. free() is supported but does nothing.
2411 The memory will be freed (or in fact just forgotten) when
2412 U-Boot relocates itself.
2414 - CONFIG_SYS_MALLOC_SIMPLE
2415 Provides a simple and small malloc() and calloc() for those
2416 boards which do not use the full malloc in SPL (which is
2417 enabled with CONFIG_SYS_SPL_MALLOC_START).
2419 - CONFIG_SYS_NONCACHED_MEMORY:
2420 Size of non-cached memory area. This area of memory will be
2421 typically located right below the malloc() area and mapped
2422 uncached in the MMU. This is useful for drivers that would
2423 otherwise require a lot of explicit cache maintenance. For
2424 some drivers it's also impossible to properly maintain the
2425 cache. For example if the regions that need to be flushed
2426 are not a multiple of the cache-line size, *and* padding
2427 cannot be allocated between the regions to align them (i.e.
2428 if the HW requires a contiguous array of regions, and the
2429 size of each region is not cache-aligned), then a flush of
2430 one region may result in overwriting data that hardware has
2431 written to another region in the same cache-line. This can
2432 happen for example in network drivers where descriptors for
2433 buffers are typically smaller than the CPU cache-line (e.g.
2434 16 bytes vs. 32 or 64 bytes).
2436 Non-cached memory is only supported on 32-bit ARM at present.
2438 - CONFIG_SYS_BOOTM_LEN:
2439 Normally compressed uImages are limited to an
2440 uncompressed size of 8 MBytes. If this is not enough,
2441 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2442 to adjust this setting to your needs.
2444 - CONFIG_SYS_BOOTMAPSZ:
2445 Maximum size of memory mapped by the startup code of
2446 the Linux kernel; all data that must be processed by
2447 the Linux kernel (bd_info, boot arguments, FDT blob if
2448 used) must be put below this limit, unless "bootm_low"
2449 environment variable is defined and non-zero. In such case
2450 all data for the Linux kernel must be between "bootm_low"
2451 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2452 variable "bootm_mapsize" will override the value of
2453 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2454 then the value in "bootm_size" will be used instead.
2456 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2457 Enable initrd_high functionality. If defined then the
2458 initrd_high feature is enabled and the bootm ramdisk subcommand
2459 is enabled.
2461 - CONFIG_SYS_BOOT_GET_CMDLINE:
2462 Enables allocating and saving kernel cmdline in space between
2463 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2465 - CONFIG_SYS_BOOT_GET_KBD:
2466 Enables allocating and saving a kernel copy of the bd_info in
2467 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2469 - CONFIG_SYS_MAX_FLASH_BANKS:
2470 Max number of Flash memory banks
2472 - CONFIG_SYS_MAX_FLASH_SECT:
2473 Max number of sectors on a Flash chip
2475 - CONFIG_SYS_FLASH_ERASE_TOUT:
2476 Timeout for Flash erase operations (in ms)
2478 - CONFIG_SYS_FLASH_WRITE_TOUT:
2479 Timeout for Flash write operations (in ms)
2481 - CONFIG_SYS_FLASH_LOCK_TOUT
2482 Timeout for Flash set sector lock bit operation (in ms)
2484 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2485 Timeout for Flash clear lock bits operation (in ms)
2487 - CONFIG_SYS_FLASH_PROTECTION
2488 If defined, hardware flash sectors protection is used
2489 instead of U-Boot software protection.
2491 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2493 Enable TFTP transfers directly to flash memory;
2494 without this option such a download has to be
2495 performed in two steps: (1) download to RAM, and (2)
2496 copy from RAM to flash.
2498 The two-step approach is usually more reliable, since
2499 you can check if the download worked before you erase
2500 the flash, but in some situations (when system RAM is
2501 too limited to allow for a temporary copy of the
2502 downloaded image) this option may be very useful.
2504 - CONFIG_SYS_FLASH_CFI:
2505 Define if the flash driver uses extra elements in the
2506 common flash structure for storing flash geometry.
2508 - CONFIG_FLASH_CFI_DRIVER
2509 This option also enables the building of the cfi_flash driver
2510 in the drivers directory
2512 - CONFIG_FLASH_CFI_MTD
2513 This option enables the building of the cfi_mtd driver
2514 in the drivers directory. The driver exports CFI flash
2515 to the MTD layer.
2517 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2518 Use buffered writes to flash.
2520 - CONFIG_FLASH_SPANSION_S29WS_N
2521 s29ws-n MirrorBit flash has non-standard addresses for buffered
2522 write commands.
2524 - CONFIG_SYS_FLASH_QUIET_TEST
2525 If this option is defined, the common CFI flash doesn't
2526 print it's warning upon not recognized FLASH banks. This
2527 is useful, if some of the configured banks are only
2528 optionally available.
2530 - CONFIG_FLASH_SHOW_PROGRESS
2531 If defined (must be an integer), print out countdown
2532 digits and dots. Recommended value: 45 (9..1) for 80
2533 column displays, 15 (3..1) for 40 column displays.
2535 - CONFIG_FLASH_VERIFY
2536 If defined, the content of the flash (destination) is compared
2537 against the source after the write operation. An error message
2538 will be printed when the contents are not identical.
2539 Please note that this option is useless in nearly all cases,
2540 since such flash programming errors usually are detected earlier
2541 while unprotecting/erasing/programming. Please only enable
2542 this option if you really know what you are doing.
2544 - CONFIG_SYS_RX_ETH_BUFFER:
2545 Defines the number of Ethernet receive buffers. On some
2546 Ethernet controllers it is recommended to set this value
2547 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2548 buffers can be full shortly after enabling the interface
2549 on high Ethernet traffic.
2550 Defaults to 4 if not defined.
2552 - CONFIG_ENV_MAX_ENTRIES
2554 Maximum number of entries in the hash table that is used
2555 internally to store the environment settings. The default
2556 setting is supposed to be generous and should work in most
2557 cases. This setting can be used to tune behaviour; see
2558 lib/hashtable.c for details.
2560 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2561 - CONFIG_ENV_FLAGS_LIST_STATIC
2562 Enable validation of the values given to environment variables when
2563 calling env set. Variables can be restricted to only decimal,
2564 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2565 the variables can also be restricted to IP address or MAC address.
2567 The format of the list is:
2568 type_attribute = [s|d|x|b|i|m]
2569 access_attribute = [a|r|o|c]
2570 attributes = type_attribute[access_attribute]
2571 entry = variable_name[:attributes]
2572 list = entry[,list]
2574 The type attributes are:
2575 s - String (default)
2576 d - Decimal
2577 x - Hexadecimal
2578 b - Boolean ([1yYtT|0nNfF])
2579 i - IP address
2580 m - MAC address
2582 The access attributes are:
2583 a - Any (default)
2584 r - Read-only
2585 o - Write-once
2586 c - Change-default
2588 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2589 Define this to a list (string) to define the ".flags"
2590 environment variable in the default or embedded environment.
2592 - CONFIG_ENV_FLAGS_LIST_STATIC
2593 Define this to a list (string) to define validation that
2594 should be done if an entry is not found in the ".flags"
2595 environment variable. To override a setting in the static
2596 list, simply add an entry for the same variable name to the
2597 ".flags" variable.
2599 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2600 regular expression. This allows multiple variables to define the same
2601 flags without explicitly listing them for each variable.
2603 The following definitions that deal with the placement and management
2604 of environment data (variable area); in general, we support the
2605 following configurations:
2607 - CONFIG_BUILD_ENVCRC:
2609 Builds up envcrc with the target environment so that external utils
2610 may easily extract it and embed it in final U-Boot images.
2612 BE CAREFUL! The first access to the environment happens quite early
2613 in U-Boot initialization (when we try to get the setting of for the
2614 console baudrate). You *MUST* have mapped your NVRAM area then, or
2615 U-Boot will hang.
2617 Please note that even with NVRAM we still use a copy of the
2618 environment in RAM: we could work on NVRAM directly, but we want to
2619 keep settings there always unmodified except somebody uses "saveenv"
2620 to save the current settings.
2622 BE CAREFUL! For some special cases, the local device can not use
2623 "saveenv" command. For example, the local device will get the
2624 environment stored in a remote NOR flash by SRIO or PCIE link,
2625 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2627 - CONFIG_NAND_ENV_DST
2629 Defines address in RAM to which the nand_spl code should copy the
2630 environment. If redundant environment is used, it will be copied to
2631 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2633 Please note that the environment is read-only until the monitor
2634 has been relocated to RAM and a RAM copy of the environment has been
2635 created; also, when using EEPROM you will have to use env_get_f()
2636 until then to read environment variables.
2638 The environment is protected by a CRC32 checksum. Before the monitor
2639 is relocated into RAM, as a result of a bad CRC you will be working
2640 with the compiled-in default environment - *silently*!!! [This is
2641 necessary, because the first environment variable we need is the
2642 "baudrate" setting for the console - if we have a bad CRC, we don't
2643 have any device yet where we could complain.]
2645 Note: once the monitor has been relocated, then it will complain if
2646 the default environment is used; a new CRC is computed as soon as you
2647 use the "saveenv" command to store a valid environment.
2649 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2650 Echo the inverted Ethernet link state to the fault LED.
2652 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2653 also needs to be defined.
2655 - CONFIG_SYS_FAULT_MII_ADDR:
2656 MII address of the PHY to check for the Ethernet link state.
2658 - CONFIG_NS16550_MIN_FUNCTIONS:
2659 Define this if you desire to only have use of the NS16550_init
2660 and NS16550_putc functions for the serial driver located at
2661 drivers/serial/ns16550.c. This option is useful for saving
2662 space for already greatly restricted images, including but not
2663 limited to NAND_SPL configurations.
2665 - CONFIG_DISPLAY_BOARDINFO
2666 Display information about the board that U-Boot is running on
2667 when U-Boot starts up. The board function checkboard() is called
2668 to do this.
2670 - CONFIG_DISPLAY_BOARDINFO_LATE
2671 Similar to the previous option, but display this information
2672 later, once stdio is running and output goes to the LCD, if
2673 present.
2675 - CONFIG_BOARD_SIZE_LIMIT:
2676 Maximum size of the U-Boot image. When defined, the
2677 build system checks that the actual size does not
2678 exceed it.
2680 Low Level (hardware related) configuration options:
2681 ---------------------------------------------------
2683 - CONFIG_SYS_CACHELINE_SIZE:
2684 Cache Line Size of the CPU.
2686 - CONFIG_SYS_CCSRBAR_DEFAULT:
2687 Default (power-on reset) physical address of CCSR on Freescale
2688 PowerPC SOCs.
2690 - CONFIG_SYS_CCSRBAR:
2691 Virtual address of CCSR. On a 32-bit build, this is typically
2692 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2694 - CONFIG_SYS_CCSRBAR_PHYS:
2695 Physical address of CCSR. CCSR can be relocated to a new
2696 physical address, if desired. In this case, this macro should
2697 be set to that address. Otherwise, it should be set to the
2698 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2699 is typically relocated on 36-bit builds. It is recommended
2700 that this macro be defined via the _HIGH and _LOW macros:
2702 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2703 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2705 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2706 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2707 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2708 used in assembly code, so it must not contain typecasts or
2709 integer size suffixes (e.g. "ULL").
2711 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2712 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2713 used in assembly code, so it must not contain typecasts or
2714 integer size suffixes (e.g. "ULL").
2716 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2717 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2718 forced to a value that ensures that CCSR is not relocated.
2720 - CONFIG_IDE_AHB:
2721 Most IDE controllers were designed to be connected with PCI
2722 interface. Only few of them were designed for AHB interface.
2723 When software is doing ATA command and data transfer to
2724 IDE devices through IDE-AHB controller, some additional
2725 registers accessing to these kind of IDE-AHB controller
2726 is required.
2728 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2729 DO NOT CHANGE unless you know exactly what you're
2730 doing! (11-4) [MPC8xx systems only]
2732 - CONFIG_SYS_INIT_RAM_ADDR:
2734 Start address of memory area that can be used for
2735 initial data and stack; please note that this must be
2736 writable memory that is working WITHOUT special
2737 initialization, i. e. you CANNOT use normal RAM which
2738 will become available only after programming the
2739 memory controller and running certain initialization
2740 sequences.
2742 U-Boot uses the following memory types:
2743 - MPC8xx: IMMR (internal memory of the CPU)
2745 - CONFIG_SYS_GBL_DATA_OFFSET:
2747 Offset of the initial data structure in the memory
2748 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2749 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2750 data is located at the end of the available space
2751 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2752 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2753 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2754 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2756 Note:
2757 On the MPC824X (or other systems that use the data
2758 cache for initial memory) the address chosen for
2759 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2760 point to an otherwise UNUSED address space between
2761 the top of RAM and the start of the PCI space.
2763 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2765 - CONFIG_SYS_OR_TIMING_SDRAM:
2766 SDRAM timing
2768 - CONFIG_SYS_MAMR_PTA:
2769 periodic timer for refresh
2771 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2772 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2773 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2774 CONFIG_SYS_BR1_PRELIM:
2775 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2777 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2778 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2779 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2780 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2782 - CONFIG_PCI_ENUM_ONLY
2783 Only scan through and get the devices on the buses.
2784 Don't do any setup work, presumably because someone or
2785 something has already done it, and we don't need to do it
2786 a second time. Useful for platforms that are pre-booted
2787 by coreboot or similar.
2789 - CONFIG_PCI_INDIRECT_BRIDGE:
2790 Enable support for indirect PCI bridges.
2792 - CONFIG_SYS_SRIO:
2793 Chip has SRIO or not
2795 - CONFIG_SRIO1:
2796 Board has SRIO 1 port available
2798 - CONFIG_SRIO2:
2799 Board has SRIO 2 port available
2801 - CONFIG_SRIO_PCIE_BOOT_MASTER
2802 Board can support master function for Boot from SRIO and PCIE
2804 - CONFIG_SYS_SRIOn_MEM_VIRT:
2805 Virtual Address of SRIO port 'n' memory region
2807 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2808 Physical Address of SRIO port 'n' memory region
2810 - CONFIG_SYS_SRIOn_MEM_SIZE:
2811 Size of SRIO port 'n' memory region
2813 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2814 Defined to tell the NAND controller that the NAND chip is using
2815 a 16 bit bus.
2816 Not all NAND drivers use this symbol.
2817 Example of drivers that use it:
2818 - drivers/mtd/nand/raw/ndfc.c
2819 - drivers/mtd/nand/raw/mxc_nand.c
2821 - CONFIG_SYS_NDFC_EBC0_CFG
2822 Sets the EBC0_CFG register for the NDFC. If not defined
2823 a default value will be used.
2825 - CONFIG_SPD_EEPROM
2826 Get DDR timing information from an I2C EEPROM. Common
2827 with pluggable memory modules such as SODIMMs
2829 SPD_EEPROM_ADDRESS
2830 I2C address of the SPD EEPROM
2832 - CONFIG_SYS_SPD_BUS_NUM
2833 If SPD EEPROM is on an I2C bus other than the first
2834 one, specify here. Note that the value must resolve
2835 to something your driver can deal with.
2837 - CONFIG_SYS_DDR_RAW_TIMING
2838 Get DDR timing information from other than SPD. Common with
2839 soldered DDR chips onboard without SPD. DDR raw timing
2840 parameters are extracted from datasheet and hard-coded into
2841 header files or board specific files.
2843 - CONFIG_FSL_DDR_INTERACTIVE
2844 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2846 - CONFIG_FSL_DDR_SYNC_REFRESH
2847 Enable sync of refresh for multiple controllers.
2849 - CONFIG_FSL_DDR_BIST
2850 Enable built-in memory test for Freescale DDR controllers.
2852 - CONFIG_SYS_83XX_DDR_USES_CS0
2853 Only for 83xx systems. If specified, then DDR should
2854 be configured using CS0 and CS1 instead of CS2 and CS3.
2856 - CONFIG_RMII
2857 Enable RMII mode for all FECs.
2858 Note that this is a global option, we can't
2859 have one FEC in standard MII mode and another in RMII mode.
2861 - CONFIG_CRC32_VERIFY
2862 Add a verify option to the crc32 command.
2863 The syntax is:
2865 => crc32 -v <address> <count> <crc32>
2867 Where address/count indicate a memory area
2868 and crc32 is the correct crc32 which the
2869 area should have.
2871 - CONFIG_LOOPW
2872 Add the "loopw" memory command. This only takes effect if
2873 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2875 - CONFIG_CMD_MX_CYCLIC
2876 Add the "mdc" and "mwc" memory commands. These are cyclic
2877 "md/mw" commands.
2878 Examples:
2880 => mdc.b 10 4 500
2881 This command will print 4 bytes (10,11,12,13) each 500 ms.
2883 => mwc.l 100 12345678 10
2884 This command will write 12345678 to address 100 all 10 ms.
2886 This only takes effect if the memory commands are activated
2887 globally (CONFIG_CMD_MEMORY).
2889 - CONFIG_SKIP_LOWLEVEL_INIT
2890 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain
2891 low level initializations (like setting up the memory
2892 controller) are omitted and/or U-Boot does not
2893 relocate itself into RAM.
2895 Normally this variable MUST NOT be defined. The only
2896 exception is when U-Boot is loaded (to RAM) by some
2897 other boot loader or by a debugger which performs
2898 these initializations itself.
2900 - CONFIG_SKIP_LOWLEVEL_INIT_ONLY
2901 [ARM926EJ-S only] This allows just the call to lowlevel_init()
2902 to be skipped. The normal CP15 init (such as enabling the
2903 instruction cache) is still performed.
2905 - CONFIG_SPL_BUILD
2906 Set when the currently-running compilation is for an artifact
2907 that will end up in the SPL (as opposed to the TPL or U-Boot
2908 proper). Code that needs stage-specific behavior should check
2909 this.
2911 - CONFIG_TPL_BUILD
2912 Set when the currently-running compilation is for an artifact
2913 that will end up in the TPL (as opposed to the SPL or U-Boot
2914 proper). Code that needs stage-specific behavior should check
2915 this.
2917 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2918 Only for 85xx systems. If this variable is specified, the section
2919 .resetvec is not kept and the section .bootpg is placed in the
2920 previous 4k of the .text section.
2922 - CONFIG_ARCH_MAP_SYSMEM
2923 Generally U-Boot (and in particular the md command) uses
2924 effective address. It is therefore not necessary to regard
2925 U-Boot address as virtual addresses that need to be translated
2926 to physical addresses. However, sandbox requires this, since
2927 it maintains its own little RAM buffer which contains all
2928 addressable memory. This option causes some memory accesses
2929 to be mapped through map_sysmem() / unmap_sysmem().
2931 - CONFIG_X86_RESET_VECTOR
2932 If defined, the x86 reset vector code is included. This is not
2933 needed when U-Boot is running from Coreboot.
2935 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2936 Option to disable subpage write in NAND driver
2937 driver that uses this:
2938 drivers/mtd/nand/raw/davinci_nand.c
2940 Freescale QE/FMAN Firmware Support:
2941 -----------------------------------
2943 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2944 loading of "firmware", which is encoded in the QE firmware binary format.
2945 This firmware often needs to be loaded during U-Boot booting, so macros
2946 are used to identify the storage device (NOR flash, SPI, etc) and the address
2947 within that device.
2949 - CONFIG_SYS_FMAN_FW_ADDR
2950 The address in the storage device where the FMAN microcode is located. The
2951 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2952 is also specified.
2954 - CONFIG_SYS_QE_FW_ADDR
2955 The address in the storage device where the QE microcode is located. The
2956 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2957 is also specified.
2959 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2960 The maximum possible size of the firmware. The firmware binary format
2961 has a field that specifies the actual size of the firmware, but it
2962 might not be possible to read any part of the firmware unless some
2963 local storage is allocated to hold the entire firmware first.
2965 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2966 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2967 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2968 virtual address in NOR flash.
2970 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2971 Specifies that QE/FMAN firmware is located in NAND flash.
2972 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2974 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2975 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2976 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2978 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2979 Specifies that QE/FMAN firmware is located in the remote (master)
2980 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2981 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2982 window->master inbound window->master LAW->the ucode address in
2983 master's memory space.
2985 Freescale Layerscape Management Complex Firmware Support:
2986 ---------------------------------------------------------
2987 The Freescale Layerscape Management Complex (MC) supports the loading of
2988 "firmware".
2989 This firmware often needs to be loaded during U-Boot booting, so macros
2990 are used to identify the storage device (NOR flash, SPI, etc) and the address
2991 within that device.
2993 - CONFIG_FSL_MC_ENET
2994 Enable the MC driver for Layerscape SoCs.
2996 Freescale Layerscape Debug Server Support:
2997 -------------------------------------------
2998 The Freescale Layerscape Debug Server Support supports the loading of
2999 "Debug Server firmware" and triggering SP boot-rom.
3000 This firmware often needs to be loaded during U-Boot booting.
3002 - CONFIG_SYS_MC_RSV_MEM_ALIGN
3003 Define alignment of reserved memory MC requires
3005 Reproducible builds
3006 -------------------
3008 In order to achieve reproducible builds, timestamps used in the U-Boot build
3009 process have to be set to a fixed value.
3011 This is done using the SOURCE_DATE_EPOCH environment variable.
3012 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
3013 option for U-Boot or an environment variable in U-Boot.
3015 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
3017 Building the Software:
3018 ======================
3020 Building U-Boot has been tested in several native build environments
3021 and in many different cross environments. Of course we cannot support
3022 all possibly existing versions of cross development tools in all
3023 (potentially obsolete) versions. In case of tool chain problems we
3024 recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3025 which is extensively used to build and test U-Boot.
3027 If you are not using a native environment, it is assumed that you
3028 have GNU cross compiling tools available in your path. In this case,
3029 you must set the environment variable CROSS_COMPILE in your shell.
3030 Note that no changes to the Makefile or any other source files are
3031 necessary. For example using the ELDK on a 4xx CPU, please enter:
3033 $ CROSS_COMPILE=ppc_4xx-
3034 $ export CROSS_COMPILE
3036 U-Boot is intended to be simple to build. After installing the
3037 sources you must configure U-Boot for one specific board type. This
3038 is done by typing:
3040 make NAME_defconfig
3042 where "NAME_defconfig" is the name of one of the existing configu-
3043 rations; see configs/*_defconfig for supported names.
3045 Note: for some boards special configuration names may exist; check if
3046 additional information is available from the board vendor; for
3047 instance, the TQM823L systems are available without (standard)
3048 or with LCD support. You can select such additional "features"
3049 when choosing the configuration, i. e.
3051 make TQM823L_defconfig
3052 - will configure for a plain TQM823L, i. e. no LCD support
3054 make TQM823L_LCD_defconfig
3055 - will configure for a TQM823L with U-Boot console on LCD
3057 etc.
3060 Finally, type "make all", and you should get some working U-Boot
3061 images ready for download to / installation on your system:
3063 - "u-boot.bin" is a raw binary image
3064 - "u-boot" is an image in ELF binary format
3065 - "u-boot.srec" is in Motorola S-Record format
3067 By default the build is performed locally and the objects are saved
3068 in the source directory. One of the two methods can be used to change
3069 this behavior and build U-Boot to some external directory:
3071 1. Add O= to the make command line invocations:
3073 make O=/tmp/build distclean
3074 make O=/tmp/build NAME_defconfig
3075 make O=/tmp/build all
3077 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
3079 export KBUILD_OUTPUT=/tmp/build
3080 make distclean
3081 make NAME_defconfig
3082 make all
3084 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
3085 variable.
3087 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
3088 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
3089 For example to treat all compiler warnings as errors:
3091 make KCFLAGS=-Werror
3093 Please be aware that the Makefiles assume you are using GNU make, so
3094 for instance on NetBSD you might need to use "gmake" instead of
3095 native "make".
3098 If the system board that you have is not listed, then you will need
3099 to port U-Boot to your hardware platform. To do this, follow these
3100 steps:
3102 1. Create a new directory to hold your board specific code. Add any
3103 files you need. In your board directory, you will need at least
3104 the "Makefile" and a "<board>.c".
3105 2. Create a new configuration file "include/configs/<board>.h" for
3106 your board.
3107 3. If you're porting U-Boot to a new CPU, then also create a new
3108 directory to hold your CPU specific code. Add any files you need.
3109 4. Run "make <board>_defconfig" with your new name.
3110 5. Type "make", and you should get a working "u-boot.srec" file
3111 to be installed on your target system.
3112 6. Debug and solve any problems that might arise.
3113 [Of course, this last step is much harder than it sounds.]
3116 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3117 ==============================================================
3119 If you have modified U-Boot sources (for instance added a new board
3120 or support for new devices, a new CPU, etc.) you are expected to
3121 provide feedback to the other developers. The feedback normally takes
3122 the form of a "patch", i.e. a context diff against a certain (latest
3123 official or latest in the git repository) version of U-Boot sources.
3125 But before you submit such a patch, please verify that your modifi-
3126 cation did not break existing code. At least make sure that *ALL* of
3127 the supported boards compile WITHOUT ANY compiler warnings. To do so,
3128 just run the buildman script (tools/buildman/buildman), which will
3129 configure and build U-Boot for ALL supported system. Be warned, this
3130 will take a while. Please see the buildman README, or run 'buildman -H'
3131 for documentation.
3134 See also "U-Boot Porting Guide" below.
3137 Monitor Commands - Overview:
3138 ============================
3140 go - start application at address 'addr'
3141 run - run commands in an environment variable
3142 bootm - boot application image from memory
3143 bootp - boot image via network using BootP/TFTP protocol
3144 bootz - boot zImage from memory
3145 tftpboot- boot image via network using TFTP protocol
3146 and env variables "ipaddr" and "serverip"
3147 (and eventually "gatewayip")
3148 tftpput - upload a file via network using TFTP protocol
3149 rarpboot- boot image via network using RARP/TFTP protocol
3150 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
3151 loads - load S-Record file over serial line
3152 loadb - load binary file over serial line (kermit mode)
3153 md - memory display
3154 mm - memory modify (auto-incrementing)
3155 nm - memory modify (constant address)
3156 mw - memory write (fill)
3157 ms - memory search
3158 cp - memory copy
3159 cmp - memory compare
3160 crc32 - checksum calculation
3161 i2c - I2C sub-system
3162 sspi - SPI utility commands
3163 base - print or set address offset
3164 printenv- print environment variables
3165 setenv - set environment variables
3166 saveenv - save environment variables to persistent storage
3167 protect - enable or disable FLASH write protection
3168 erase - erase FLASH memory
3169 flinfo - print FLASH memory information
3170 nand - NAND memory operations (see doc/README.nand)
3171 bdinfo - print Board Info structure
3172 iminfo - print header information for application image
3173 coninfo - print console devices and informations
3174 ide - IDE sub-system
3175 loop - infinite loop on address range
3176 loopw - infinite write loop on address range
3177 mtest - simple RAM test
3178 icache - enable or disable instruction cache
3179 dcache - enable or disable data cache
3180 reset - Perform RESET of the CPU
3181 echo - echo args to console
3182 version - print monitor version
3183 help - print online help
3184 ? - alias for 'help'
3187 Monitor Commands - Detailed Description:
3188 ========================================
3190 TODO.
3192 For now: just type "help <command>".
3195 Environment Variables:
3196 ======================
3198 U-Boot supports user configuration using Environment Variables which
3199 can be made persistent by saving to Flash memory.
3201 Environment Variables are set using "setenv", printed using
3202 "printenv", and saved to Flash using "saveenv". Using "setenv"
3203 without a value can be used to delete a variable from the
3204 environment. As long as you don't save the environment you are
3205 working with an in-memory copy. In case the Flash area containing the
3206 environment is erased by accident, a default environment is provided.
3208 Some configuration options can be set using Environment Variables.
3210 List of environment variables (most likely not complete):
3212 baudrate - see CONFIG_BAUDRATE
3214 bootdelay - see CONFIG_BOOTDELAY
3216 bootcmd - see CONFIG_BOOTCOMMAND
3218 bootargs - Boot arguments when booting an RTOS image
3220 bootfile - Name of the image to load with TFTP
3222 bootm_low - Memory range available for image processing in the bootm
3223 command can be restricted. This variable is given as
3224 a hexadecimal number and defines lowest address allowed
3225 for use by the bootm command. See also "bootm_size"
3226 environment variable. Address defined by "bootm_low" is
3227 also the base of the initial memory mapping for the Linux
3228 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3229 bootm_mapsize.
3231 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3232 This variable is given as a hexadecimal number and it
3233 defines the size of the memory region starting at base
3234 address bootm_low that is accessible by the Linux kernel
3235 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3236 as the default value if it is defined, and bootm_size is
3237 used otherwise.
3239 bootm_size - Memory range available for image processing in the bootm
3240 command can be restricted. This variable is given as
3241 a hexadecimal number and defines the size of the region
3242 allowed for use by the bootm command. See also "bootm_low"
3243 environment variable.
3245 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot
3247 updatefile - Location of the software update file on a TFTP server, used
3248 by the automatic software update feature. Please refer to
3249 documentation in doc/README.update for more details.
3251 autoload - if set to "no" (any string beginning with 'n'),
3252 "bootp" will just load perform a lookup of the
3253 configuration from the BOOTP server, but not try to
3254 load any image using TFTP
3256 autostart - if set to "yes", an image loaded using the "bootp",
3257 "rarpboot", "tftpboot" or "diskboot" commands will
3258 be automatically started (by internally calling
3259 "bootm")
3261 If set to "no", a standalone image passed to the
3262 "bootm" command will be copied to the load address
3263 (and eventually uncompressed), but NOT be started.
3264 This can be used to load and uncompress arbitrary
3265 data.
3267 fdt_high - if set this restricts the maximum address that the
3268 flattened device tree will be copied into upon boot.
3269 For example, if you have a system with 1 GB memory
3270 at physical address 0x10000000, while Linux kernel
3271 only recognizes the first 704 MB as low memory, you
3272 may need to set fdt_high as 0x3C000000 to have the
3273 device tree blob be copied to the maximum address
3274 of the 704 MB low memory, so that Linux kernel can
3275 access it during the boot procedure.
3277 If this is set to the special value 0xFFFFFFFF then
3278 the fdt will not be copied at all on boot. For this
3279 to work it must reside in writable memory, have
3280 sufficient padding on the end of it for u-boot to
3281 add the information it needs into it, and the memory
3282 must be accessible by the kernel.
3284 fdtcontroladdr- if set this is the address of the control flattened
3285 device tree used by U-Boot when CONFIG_OF_CONTROL is
3286 defined.
3288 i2cfast - (PPC405GP|PPC405EP only)
3289 if set to 'y' configures Linux I2C driver for fast
3290 mode (400kHZ). This environment variable is used in
3291 initialization code. So, for changes to be effective
3292 it must be saved and board must be reset.
3294 initrd_high - restrict positioning of initrd images:
3295 If this variable is not set, initrd images will be
3296 copied to the highest possible address in RAM; this
3297 is usually what you want since it allows for
3298 maximum initrd size. If for some reason you want to
3299 make sure that the initrd image is loaded below the
3300 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3301 variable to a value of "no" or "off" or "0".
3302 Alternatively, you can set it to a maximum upper
3303 address to use (U-Boot will still check that it
3304 does not overwrite the U-Boot stack and data).
3306 For instance, when you have a system with 16 MB
3307 RAM, and want to reserve 4 MB from use by Linux,
3308 you can do this by adding "mem=12M" to the value of
3309 the "bootargs" variable. However, now you must make
3310 sure that the initrd image is placed in the first
3311 12 MB as well - this can be done with
3313 setenv initrd_high 00c00000
3315 If you set initrd_high to 0xFFFFFFFF, this is an
3316 indication to U-Boot that all addresses are legal
3317 for the Linux kernel, including addresses in flash
3318 memory. In this case U-Boot will NOT COPY the
3319 ramdisk at all. This may be useful to reduce the
3320 boot time on your system, but requires that this
3321 feature is supported by your Linux kernel.
3323 ipaddr - IP address; needed for tftpboot command
3325 loadaddr - Default load address for commands like "bootp",
3326 "rarpboot", "tftpboot", "loadb" or "diskboot"
3328 loads_echo - see CONFIG_LOADS_ECHO
3330 serverip - TFTP server IP address; needed for tftpboot command
3332 bootretry - see CONFIG_BOOT_RETRY_TIME
3334 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3336 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3338 ethprime - controls which interface is used first.
3340 ethact - controls which interface is currently active.
3341 For example you can do the following
3343 => setenv ethact FEC
3344 => ping 192.168.0.1 # traffic sent on FEC
3345 => setenv ethact SCC
3346 => ping 10.0.0.1 # traffic sent on SCC
3348 ethrotate - When set to "no" U-Boot does not go through all
3349 available network interfaces.
3350 It just stays at the currently selected interface.
3352 netretry - When set to "no" each network operation will
3353 either succeed or fail without retrying.
3354 When set to "once" the network operation will
3355 fail when all the available network interfaces
3356 are tried once without success.
3357 Useful on scripts which control the retry operation
3358 themselves.
3360 npe_ucode - set load address for the NPE microcode
3362 silent_linux - If set then Linux will be told to boot silently, by
3363 changing the console to be empty. If "yes" it will be
3364 made silent. If "no" it will not be made silent. If
3365 unset, then it will be made silent if the U-Boot console
3366 is silent.
3368 tftpsrcp - If this is set, the value is used for TFTP's
3369 UDP source port.
3371 tftpdstp - If this is set, the value is used for TFTP's UDP
3372 destination port instead of the Well Know Port 69.
3374 tftpblocksize - Block size to use for TFTP transfers; if not set,
3375 we use the TFTP server's default block size
3377 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3378 seconds, minimum value is 1000 = 1 second). Defines
3379 when a packet is considered to be lost so it has to
3380 be retransmitted. The default is 5000 = 5 seconds.
3381 Lowering this value may make downloads succeed
3382 faster in networks with high packet loss rates or
3383 with unreliable TFTP servers.
3385 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3386 unit, minimum value = 0). Defines how many timeouts
3387 can happen during a single file transfer before that
3388 transfer is aborted. The default is 10, and 0 means
3389 'no timeouts allowed'. Increasing this value may help
3390 downloads succeed with high packet loss rates, or with
3391 unreliable TFTP servers or client hardware.
3393 tftpwindowsize - if this is set, the value is used for TFTP's
3394 window size as described by RFC 7440.
3395 This means the count of blocks we can receive before
3396 sending ack to server.
3398 vlan - When set to a value < 4095 the traffic over
3399 Ethernet is encapsulated/received over 802.1q
3400 VLAN tagged frames.
3402 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3403 Unsigned value, in milliseconds. If not set, the period will
3404 be either the default (28000), or a value based on
3405 CONFIG_NET_RETRY_COUNT, if defined. This value has
3406 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3408 memmatches - Number of matches found by the last 'ms' command, in hex
3410 memaddr - Address of the last match found by the 'ms' command, in hex,
3411 or 0 if none
3413 mempos - Index position of the last match found by the 'ms' command,
3414 in units of the size (.b, .w, .l) of the search
3416 zbootbase - (x86 only) Base address of the bzImage 'setup' block
3418 zbootaddr - (x86 only) Address of the loaded bzImage, typically
3419 BZIMAGE_LOAD_ADDR which is 0x100000
3421 The following image location variables contain the location of images
3422 used in booting. The "Image" column gives the role of the image and is
3423 not an environment variable name. The other columns are environment
3424 variable names. "File Name" gives the name of the file on a TFTP
3425 server, "RAM Address" gives the location in RAM the image will be
3426 loaded to, and "Flash Location" gives the image's address in NOR
3427 flash or offset in NAND flash.
3429 *Note* - these variables don't have to be defined for all boards, some
3430 boards currently use other variables for these purposes, and some
3431 boards use these variables for other purposes.
3433 Image File Name RAM Address Flash Location
3434 ----- --------- ----------- --------------
3435 u-boot u-boot u-boot_addr_r u-boot_addr
3436 Linux kernel bootfile kernel_addr_r kernel_addr
3437 device tree blob fdtfile fdt_addr_r fdt_addr
3438 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3440 The following environment variables may be used and automatically
3441 updated by the network boot commands ("bootp" and "rarpboot"),
3442 depending the information provided by your boot server:
3444 bootfile - see above
3445 dnsip - IP address of your Domain Name Server
3446 dnsip2 - IP address of your secondary Domain Name Server
3447 gatewayip - IP address of the Gateway (Router) to use
3448 hostname - Target hostname
3449 ipaddr - see above
3450 netmask - Subnet Mask
3451 rootpath - Pathname of the root filesystem on the NFS server
3452 serverip - see above
3455 There are two special Environment Variables:
3457 serial# - contains hardware identification information such
3458 as type string and/or serial number
3459 ethaddr - Ethernet address
3461 These variables can be set only once (usually during manufacturing of
3462 the board). U-Boot refuses to delete or overwrite these variables
3463 once they have been set once.
3466 Further special Environment Variables:
3468 ver - Contains the U-Boot version string as printed
3469 with the "version" command. This variable is
3470 readonly (see CONFIG_VERSION_VARIABLE).
3473 Please note that changes to some configuration parameters may take
3474 only effect after the next boot (yes, that's just like Windoze :-).
3477 Callback functions for environment variables:
3478 ---------------------------------------------
3480 For some environment variables, the behavior of u-boot needs to change
3481 when their values are changed. This functionality allows functions to
3482 be associated with arbitrary variables. On creation, overwrite, or
3483 deletion, the callback will provide the opportunity for some side
3484 effect to happen or for the change to be rejected.
3486 The callbacks are named and associated with a function using the
3487 U_BOOT_ENV_CALLBACK macro in your board or driver code.
3489 These callbacks are associated with variables in one of two ways. The
3490 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
3491 in the board configuration to a string that defines a list of
3492 associations. The list must be in the following format:
3494 entry = variable_name[:callback_name]
3495 list = entry[,list]
3497 If the callback name is not specified, then the callback is deleted.
3498 Spaces are also allowed anywhere in the list.
3500 Callbacks can also be associated by defining the ".callbacks" variable
3501 with the same list format above. Any association in ".callbacks" will
3502 override any association in the static list. You can define
3503 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
3504 ".callbacks" environment variable in the default or embedded environment.
3506 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3507 regular expression. This allows multiple variables to be connected to
3508 the same callback without explicitly listing them all out.
3510 The signature of the callback functions is:
3512 int callback(const char *name, const char *value, enum env_op op, int flags)
3514 * name - changed environment variable
3515 * value - new value of the environment variable
3516 * op - operation (create, overwrite, or delete)
3517 * flags - attributes of the environment variable change, see flags H_* in
3518 include/search.h
3520 The return value is 0 if the variable change is accepted and 1 otherwise.
3522 Command Line Parsing:
3523 =====================
3525 There are two different command line parsers available with U-Boot:
3526 the old "simple" one, and the much more powerful "hush" shell:
3528 Old, simple command line parser:
3529 --------------------------------
3531 - supports environment variables (through setenv / saveenv commands)
3532 - several commands on one line, separated by ';'
3533 - variable substitution using "... ${name} ..." syntax
3534 - special characters ('$', ';') can be escaped by prefixing with '\',
3535 for example:
3536 setenv bootcmd bootm \${address}
3537 - You can also escape text by enclosing in single apostrophes, for example:
3538 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3540 Hush shell:
3541 -----------
3543 - similar to Bourne shell, with control structures like
3544 if...then...else...fi, for...do...done; while...do...done,
3545 until...do...done, ...
3546 - supports environment ("global") variables (through setenv / saveenv
3547 commands) and local shell variables (through standard shell syntax
3548 "name=value"); only environment variables can be used with "run"
3549 command
3551 General rules:
3552 --------------
3554 (1) If a command line (or an environment variable executed by a "run"
3555 command) contains several commands separated by semicolon, and
3556 one of these commands fails, then the remaining commands will be
3557 executed anyway.
3559 (2) If you execute several variables with one call to run (i. e.
3560 calling run with a list of variables as arguments), any failing
3561 command will cause "run" to terminate, i. e. the remaining
3562 variables are not executed.
3564 Note for Redundant Ethernet Interfaces:
3565 =======================================
3567 Some boards come with redundant Ethernet interfaces; U-Boot supports
3568 such configurations and is capable of automatic selection of a
3569 "working" interface when needed. MAC assignment works as follows:
3571 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3572 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3573 "eth1addr" (=>eth1), "eth2addr", ...
3575 If the network interface stores some valid MAC address (for instance
3576 in SROM), this is used as default address if there is NO correspon-
3577 ding setting in the environment; if the corresponding environment
3578 variable is set, this overrides the settings in the card; that means:
3580 o If the SROM has a valid MAC address, and there is no address in the
3581 environment, the SROM's address is used.
3583 o If there is no valid address in the SROM, and a definition in the
3584 environment exists, then the value from the environment variable is
3585 used.
3587 o If both the SROM and the environment contain a MAC address, and
3588 both addresses are the same, this MAC address is used.
3590 o If both the SROM and the environment contain a MAC address, and the
3591 addresses differ, the value from the environment is used and a
3592 warning is printed.
3594 o If neither SROM nor the environment contain a MAC address, an error
3595 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
3596 a random, locally-assigned MAC is used.
3598 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
3599 will be programmed into hardware as part of the initialization process. This
3600 may be skipped by setting the appropriate 'ethmacskip' environment variable.
3601 The naming convention is as follows:
3602 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
3604 Image Formats:
3605 ==============
3607 U-Boot is capable of booting (and performing other auxiliary operations on)
3608 images in two formats:
3610 New uImage format (FIT)
3611 -----------------------
3613 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3614 to Flattened Device Tree). It allows the use of images with multiple
3615 components (several kernels, ramdisks, etc.), with contents protected by
3616 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3619 Old uImage format
3620 -----------------
3622 Old image format is based on binary files which can be basically anything,
3623 preceded by a special header; see the definitions in include/image.h for
3624 details; basically, the header defines the following image properties:
3626 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3627 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3628 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3629 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3630 INTEGRITY).
3631 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
3632 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3633 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
3634 * Compression Type (uncompressed, gzip, bzip2)
3635 * Load Address
3636 * Entry Point
3637 * Image Name
3638 * Image Timestamp
3640 The header is marked by a special Magic Number, and both the header
3641 and the data portions of the image are secured against corruption by
3642 CRC32 checksums.
3645 Linux Support:
3646 ==============
3648 Although U-Boot should support any OS or standalone application
3649 easily, the main focus has always been on Linux during the design of
3650 U-Boot.
3652 U-Boot includes many features that so far have been part of some
3653 special "boot loader" code within the Linux kernel. Also, any
3654 "initrd" images to be used are no longer part of one big Linux image;
3655 instead, kernel and "initrd" are separate images. This implementation
3656 serves several purposes:
3658 - the same features can be used for other OS or standalone
3659 applications (for instance: using compressed images to reduce the
3660 Flash memory footprint)
3662 - it becomes much easier to port new Linux kernel versions because
3663 lots of low-level, hardware dependent stuff are done by U-Boot
3665 - the same Linux kernel image can now be used with different "initrd"
3666 images; of course this also means that different kernel images can
3667 be run with the same "initrd". This makes testing easier (you don't
3668 have to build a new "zImage.initrd" Linux image when you just
3669 change a file in your "initrd"). Also, a field-upgrade of the
3670 software is easier now.
3673 Linux HOWTO:
3674 ============
3676 Porting Linux to U-Boot based systems:
3677 ---------------------------------------
3679 U-Boot cannot save you from doing all the necessary modifications to
3680 configure the Linux device drivers for use with your target hardware
3681 (no, we don't intend to provide a full virtual machine interface to
3682 Linux :-).
3684 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
3686 Just make sure your machine specific header file (for instance
3687 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3688 Information structure as we define in include/asm-<arch>/u-boot.h,
3689 and make sure that your definition of IMAP_ADDR uses the same value
3690 as your U-Boot configuration in CONFIG_SYS_IMMR.
3692 Note that U-Boot now has a driver model, a unified model for drivers.
3693 If you are adding a new driver, plumb it into driver model. If there
3694 is no uclass available, you are encouraged to create one. See
3695 doc/driver-model.
3698 Configuring the Linux kernel:
3699 -----------------------------
3701 No specific requirements for U-Boot. Make sure you have some root
3702 device (initial ramdisk, NFS) for your target system.
3705 Building a Linux Image:
3706 -----------------------
3708 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3709 not used. If you use recent kernel source, a new build target
3710 "uImage" will exist which automatically builds an image usable by
3711 U-Boot. Most older kernels also have support for a "pImage" target,
3712 which was introduced for our predecessor project PPCBoot and uses a
3713 100% compatible format.
3715 Example:
3717 make TQM850L_defconfig
3718 make oldconfig
3719 make dep
3720 make uImage
3722 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3723 encapsulate a compressed Linux kernel image with header information,
3724 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3726 * build a standard "vmlinux" kernel image (in ELF binary format):
3728 * convert the kernel into a raw binary image:
3730 ${CROSS_COMPILE}-objcopy -O binary \
3731 -R .note -R .comment \
3732 -S vmlinux linux.bin
3734 * compress the binary image:
3736 gzip -9 linux.bin
3738 * package compressed binary image for U-Boot:
3740 mkimage -A ppc -O linux -T kernel -C gzip \
3741 -a 0 -e 0 -n "Linux Kernel Image" \
3742 -d linux.bin.gz uImage
3745 The "mkimage" tool can also be used to create ramdisk images for use
3746 with U-Boot, either separated from the Linux kernel image, or
3747 combined into one file. "mkimage" encapsulates the images with a 64
3748 byte header containing information about target architecture,
3749 operating system, image type, compression method, entry points, time
3750 stamp, CRC32 checksums, etc.
3752 "mkimage" can be called in two ways: to verify existing images and
3753 print the header information, or to build new images.
3755 In the first form (with "-l" option) mkimage lists the information
3756 contained in the header of an existing U-Boot image; this includes
3757 checksum verification:
3759 tools/mkimage -l image
3760 -l ==> list image header information
3762 The second form (with "-d" option) is used to build a U-Boot image
3763 from a "data file" which is used as image payload:
3765 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3766 -n name -d data_file image
3767 -A ==> set architecture to 'arch'
3768 -O ==> set operating system to 'os'
3769 -T ==> set image type to 'type'
3770 -C ==> set compression type 'comp'
3771 -a ==> set load address to 'addr' (hex)
3772 -e ==> set entry point to 'ep' (hex)
3773 -n ==> set image name to 'name'
3774 -d ==> use image data from 'datafile'
3776 Right now, all Linux kernels for PowerPC systems use the same load
3777 address (0x00000000), but the entry point address depends on the
3778 kernel version:
3780 - 2.2.x kernels have the entry point at 0x0000000C,
3781 - 2.3.x and later kernels have the entry point at 0x00000000.
3783 So a typical call to build a U-Boot image would read:
3785 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3786 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3787 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3788 > examples/uImage.TQM850L
3789 Image Name: 2.4.4 kernel for TQM850L
3790 Created: Wed Jul 19 02:34:59 2000
3791 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3792 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3793 Load Address: 0x00000000
3794 Entry Point: 0x00000000
3796 To verify the contents of the image (or check for corruption):
3798 -> tools/mkimage -l examples/uImage.TQM850L
3799 Image Name: 2.4.4 kernel for TQM850L
3800 Created: Wed Jul 19 02:34:59 2000
3801 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3802 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3803 Load Address: 0x00000000
3804 Entry Point: 0x00000000
3806 NOTE: for embedded systems where boot time is critical you can trade
3807 speed for memory and install an UNCOMPRESSED image instead: this
3808 needs more space in Flash, but boots much faster since it does not
3809 need to be uncompressed:
3811 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3812 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3813 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3814 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3815 > examples/uImage.TQM850L-uncompressed
3816 Image Name: 2.4.4 kernel for TQM850L
3817 Created: Wed Jul 19 02:34:59 2000
3818 Image Type: PowerPC Linux Kernel Image (uncompressed)
3819 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3820 Load Address: 0x00000000
3821 Entry Point: 0x00000000
3824 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3825 when your kernel is intended to use an initial ramdisk:
3827 -> tools/mkimage -n 'Simple Ramdisk Image' \
3828 > -A ppc -O linux -T ramdisk -C gzip \
3829 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3830 Image Name: Simple Ramdisk Image
3831 Created: Wed Jan 12 14:01:50 2000
3832 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3833 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3834 Load Address: 0x00000000
3835 Entry Point: 0x00000000
3837 The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
3838 option performs the converse operation of the mkimage's second form (the "-d"
3839 option). Given an image built by mkimage, the dumpimage extracts a "data file"
3840 from the image:
3842 tools/dumpimage -i image -T type -p position data_file
3843 -i ==> extract from the 'image' a specific 'data_file'
3844 -T ==> set image type to 'type'
3845 -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
3848 Installing a Linux Image:
3849 -------------------------
3851 To downloading a U-Boot image over the serial (console) interface,
3852 you must convert the image to S-Record format:
3854 objcopy -I binary -O srec examples/image examples/image.srec
3856 The 'objcopy' does not understand the information in the U-Boot
3857 image header, so the resulting S-Record file will be relative to
3858 address 0x00000000. To load it to a given address, you need to
3859 specify the target address as 'offset' parameter with the 'loads'
3860 command.
3862 Example: install the image to address 0x40100000 (which on the
3863 TQM8xxL is in the first Flash bank):
3865 => erase 40100000 401FFFFF
3867 .......... done
3868 Erased 8 sectors
3870 => loads 40100000
3871 ## Ready for S-Record download ...
3872 ~>examples/image.srec
3873 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3874 ...
3875 15989 15990 15991 15992
3876 [file transfer complete]
3877 [connected]
3878 ## Start Addr = 0x00000000
3881 You can check the success of the download using the 'iminfo' command;
3882 this includes a checksum verification so you can be sure no data
3883 corruption happened:
3885 => imi 40100000
3887 ## Checking Image at 40100000 ...
3888 Image Name: 2.2.13 for initrd on TQM850L
3889 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3890 Data Size: 335725 Bytes = 327 kB = 0 MB
3891 Load Address: 00000000
3892 Entry Point: 0000000c
3893 Verifying Checksum ... OK
3896 Boot Linux:
3897 -----------
3899 The "bootm" command is used to boot an application that is stored in
3900 memory (RAM or Flash). In case of a Linux kernel image, the contents
3901 of the "bootargs" environment variable is passed to the kernel as
3902 parameters. You can check and modify this variable using the
3903 "printenv" and "setenv" commands:
3906 => printenv bootargs
3907 bootargs=root=/dev/ram
3909 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3911 => printenv bootargs
3912 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3914 => bootm 40020000
3915 ## Booting Linux kernel at 40020000 ...
3916 Image Name: 2.2.13 for NFS on TQM850L
3917 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3918 Data Size: 381681 Bytes = 372 kB = 0 MB
3919 Load Address: 00000000
3920 Entry Point: 0000000c
3921 Verifying Checksum ... OK
3922 Uncompressing Kernel Image ... OK
3923 Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
3924 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3925 time_init: decrementer frequency = 187500000/60
3926 Calibrating delay loop... 49.77 BogoMIPS
3927 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3928 ...
3930 If you want to boot a Linux kernel with initial RAM disk, you pass
3931 the memory addresses of both the kernel and the initrd image (PPBCOOT
3932 format!) to the "bootm" command:
3934 => imi 40100000 40200000
3936 ## Checking Image at 40100000 ...
3937 Image Name: 2.2.13 for initrd on TQM850L
3938 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3939 Data Size: 335725 Bytes = 327 kB = 0 MB
3940 Load Address: 00000000
3941 Entry Point: 0000000c
3942 Verifying Checksum ... OK
3944 ## Checking Image at 40200000 ...
3945 Image Name: Simple Ramdisk Image
3946 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3947 Data Size: 566530 Bytes = 553 kB = 0 MB
3948 Load Address: 00000000
3949 Entry Point: 00000000
3950 Verifying Checksum ... OK
3952 => bootm 40100000 40200000
3953 ## Booting Linux kernel at 40100000 ...
3954 Image Name: 2.2.13 for initrd on TQM850L
3955 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3956 Data Size: 335725 Bytes = 327 kB = 0 MB
3957 Load Address: 00000000
3958 Entry Point: 0000000c
3959 Verifying Checksum ... OK
3960 Uncompressing Kernel Image ... OK
3961 ## Loading RAMDisk Image at 40200000 ...
3962 Image Name: Simple Ramdisk Image
3963 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3964 Data Size: 566530 Bytes = 553 kB = 0 MB
3965 Load Address: 00000000
3966 Entry Point: 00000000
3967 Verifying Checksum ... OK
3968 Loading Ramdisk ... OK
3969 Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
3970 Boot arguments: root=/dev/ram
3971 time_init: decrementer frequency = 187500000/60
3972 Calibrating delay loop... 49.77 BogoMIPS
3973 ...
3974 RAMDISK: Compressed image found at block 0
3975 VFS: Mounted root (ext2 filesystem).
3977 bash#
3979 Boot Linux and pass a flat device tree:
3980 -----------
3982 First, U-Boot must be compiled with the appropriate defines. See the section
3983 titled "Linux Kernel Interface" above for a more in depth explanation. The
3984 following is an example of how to start a kernel and pass an updated
3985 flat device tree:
3987 => print oftaddr
3988 oftaddr=0x300000
3989 => print oft
3990 oft=oftrees/mpc8540ads.dtb
3991 => tftp $oftaddr $oft
3992 Speed: 1000, full duplex
3993 Using TSEC0 device
3994 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3995 Filename 'oftrees/mpc8540ads.dtb'.
3996 Load address: 0x300000
3997 Loading: #
3998 done
3999 Bytes transferred = 4106 (100a hex)
4000 => tftp $loadaddr $bootfile
4001 Speed: 1000, full duplex
4002 Using TSEC0 device
4003 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4004 Filename 'uImage'.
4005 Load address: 0x200000
4006 Loading:############
4007 done
4008 Bytes transferred = 1029407 (fb51f hex)
4009 => print loadaddr
4010 loadaddr=200000
4011 => print oftaddr
4012 oftaddr=0x300000
4013 => bootm $loadaddr - $oftaddr
4014 ## Booting image at 00200000 ...
4015 Image Name: Linux-2.6.17-dirty
4016 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4017 Data Size: 1029343 Bytes = 1005.2 kB
4018 Load Address: 00000000
4019 Entry Point: 00000000
4020 Verifying Checksum ... OK
4021 Uncompressing Kernel Image ... OK
4022 Booting using flat device tree at 0x300000
4023 Using MPC85xx ADS machine description
4024 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4025 [snip]
4028 More About U-Boot Image Types:
4029 ------------------------------
4031 U-Boot supports the following image types:
4033 "Standalone Programs" are directly runnable in the environment
4034 provided by U-Boot; it is expected that (if they behave
4035 well) you can continue to work in U-Boot after return from
4036 the Standalone Program.
4037 "OS Kernel Images" are usually images of some Embedded OS which
4038 will take over control completely. Usually these programs
4039 will install their own set of exception handlers, device
4040 drivers, set up the MMU, etc. - this means, that you cannot
4041 expect to re-enter U-Boot except by resetting the CPU.
4042 "RAMDisk Images" are more or less just data blocks, and their
4043 parameters (address, size) are passed to an OS kernel that is
4044 being started.
4045 "Multi-File Images" contain several images, typically an OS
4046 (Linux) kernel image and one or more data images like
4047 RAMDisks. This construct is useful for instance when you want
4048 to boot over the network using BOOTP etc., where the boot
4049 server provides just a single image file, but you want to get
4050 for instance an OS kernel and a RAMDisk image.
4052 "Multi-File Images" start with a list of image sizes, each
4053 image size (in bytes) specified by an "uint32_t" in network
4054 byte order. This list is terminated by an "(uint32_t)0".
4055 Immediately after the terminating 0 follow the images, one by
4056 one, all aligned on "uint32_t" boundaries (size rounded up to
4057 a multiple of 4 bytes).
4059 "Firmware Images" are binary images containing firmware (like
4060 U-Boot or FPGA images) which usually will be programmed to
4061 flash memory.
4063 "Script files" are command sequences that will be executed by
4064 U-Boot's command interpreter; this feature is especially
4065 useful when you configure U-Boot to use a real shell (hush)
4066 as command interpreter.
4068 Booting the Linux zImage:
4069 -------------------------
4071 On some platforms, it's possible to boot Linux zImage. This is done
4072 using the "bootz" command. The syntax of "bootz" command is the same
4073 as the syntax of "bootm" command.
4075 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
4076 kernel with raw initrd images. The syntax is slightly different, the
4077 address of the initrd must be augmented by it's size, in the following
4078 format: "<initrd addres>:<initrd size>".
4081 Standalone HOWTO:
4082 =================
4084 One of the features of U-Boot is that you can dynamically load and
4085 run "standalone" applications, which can use some resources of
4086 U-Boot like console I/O functions or interrupt services.
4088 Two simple examples are included with the sources:
4090 "Hello World" Demo:
4091 -------------------
4093 'examples/hello_world.c' contains a small "Hello World" Demo
4094 application; it is automatically compiled when you build U-Boot.
4095 It's configured to run at address 0x00040004, so you can play with it
4096 like that:
4098 => loads
4099 ## Ready for S-Record download ...
4100 ~>examples/hello_world.srec
4101 1 2 3 4 5 6 7 8 9 10 11 ...
4102 [file transfer complete]
4103 [connected]
4104 ## Start Addr = 0x00040004
4106 => go 40004 Hello World! This is a test.
4107 ## Starting application at 0x00040004 ...
4108 Hello World
4109 argc = 7
4110 argv[0] = "40004"
4111 argv[1] = "Hello"
4112 argv[2] = "World!"
4113 argv[3] = "This"
4114 argv[4] = "is"
4115 argv[5] = "a"
4116 argv[6] = "test."
4117 argv[7] = "<NULL>"
4118 Hit any key to exit ...
4120 ## Application terminated, rc = 0x0
4122 Another example, which demonstrates how to register a CPM interrupt
4123 handler with the U-Boot code, can be found in 'examples/timer.c'.
4124 Here, a CPM timer is set up to generate an interrupt every second.
4125 The interrupt service routine is trivial, just printing a '.'
4126 character, but this is just a demo program. The application can be
4127 controlled by the following keys:
4129 ? - print current values og the CPM Timer registers
4130 b - enable interrupts and start timer
4131 e - stop timer and disable interrupts
4132 q - quit application
4134 => loads
4135 ## Ready for S-Record download ...
4136 ~>examples/timer.srec
4137 1 2 3 4 5 6 7 8 9 10 11 ...
4138 [file transfer complete]
4139 [connected]
4140 ## Start Addr = 0x00040004
4142 => go 40004
4143 ## Starting application at 0x00040004 ...
4144 TIMERS=0xfff00980
4145 Using timer 1
4146 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4148 Hit 'b':
4149 [q, b, e, ?] Set interval 1000000 us
4150 Enabling timer
4151 Hit '?':
4152 [q, b, e, ?] ........
4153 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4154 Hit '?':
4155 [q, b, e, ?] .
4156 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4157 Hit '?':
4158 [q, b, e, ?] .
4159 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4160 Hit '?':
4161 [q, b, e, ?] .
4162 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4163 Hit 'e':
4164 [q, b, e, ?] ...Stopping timer
4165 Hit 'q':
4166 [q, b, e, ?] ## Application terminated, rc = 0x0
4169 Minicom warning:
4170 ================
4172 Over time, many people have reported problems when trying to use the
4173 "minicom" terminal emulation program for serial download. I (wd)
4174 consider minicom to be broken, and recommend not to use it. Under
4175 Unix, I recommend to use C-Kermit for general purpose use (and
4176 especially for kermit binary protocol download ("loadb" command), and
4177 use "cu" for S-Record download ("loads" command). See
4178 http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4179 for help with kermit.
4182 Nevertheless, if you absolutely want to use it try adding this
4183 configuration to your "File transfer protocols" section:
4185 Name Program Name U/D FullScr IO-Red. Multi
4186 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
4187 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
4190 NetBSD Notes:
4191 =============
4193 Starting at version 0.9.2, U-Boot supports NetBSD both as host
4194 (build U-Boot) and target system (boots NetBSD/mpc8xx).
4196 Building requires a cross environment; it is known to work on
4197 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4198 need gmake since the Makefiles are not compatible with BSD make).
4199 Note that the cross-powerpc package does not install include files;
4200 attempting to build U-Boot will fail because <machine/ansi.h> is
4201 missing. This file has to be installed and patched manually:
4203 # cd /usr/pkg/cross/powerpc-netbsd/include
4204 # mkdir powerpc
4205 # ln -s powerpc machine
4206 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4207 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
4209 Native builds *don't* work due to incompatibilities between native
4210 and U-Boot include files.
4212 Booting assumes that (the first part of) the image booted is a
4213 stage-2 loader which in turn loads and then invokes the kernel
4214 proper. Loader sources will eventually appear in the NetBSD source
4215 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4216 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4219 Implementation Internals:
4220 =========================
4222 The following is not intended to be a complete description of every
4223 implementation detail. However, it should help to understand the
4224 inner workings of U-Boot and make it easier to port it to custom
4225 hardware.
4228 Initial Stack, Global Data:
4229 ---------------------------
4231 The implementation of U-Boot is complicated by the fact that U-Boot
4232 starts running out of ROM (flash memory), usually without access to
4233 system RAM (because the memory controller is not initialized yet).
4234 This means that we don't have writable Data or BSS segments, and BSS
4235 is not initialized as zero. To be able to get a C environment working
4236 at all, we have to allocate at least a minimal stack. Implementation
4237 options for this are defined and restricted by the CPU used: Some CPU
4238 models provide on-chip memory (like the IMMR area on MPC8xx and
4239 MPC826x processors), on others (parts of) the data cache can be
4240 locked as (mis-) used as memory, etc.
4242 Chris Hallinan posted a good summary of these issues to the
4243 U-Boot mailing list:
4245 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4246 From: "Chris Hallinan" <clh@net1plus.com>
4247 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4248 ...
4250 Correct me if I'm wrong, folks, but the way I understand it
4251 is this: Using DCACHE as initial RAM for Stack, etc, does not
4252 require any physical RAM backing up the cache. The cleverness
4253 is that the cache is being used as a temporary supply of
4254 necessary storage before the SDRAM controller is setup. It's
4255 beyond the scope of this list to explain the details, but you
4256 can see how this works by studying the cache architecture and
4257 operation in the architecture and processor-specific manuals.
4259 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4260 is another option for the system designer to use as an
4261 initial stack/RAM area prior to SDRAM being available. Either
4262 option should work for you. Using CS 4 should be fine if your
4263 board designers haven't used it for something that would
4264 cause you grief during the initial boot! It is frequently not
4265 used.
4267 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4268 with your processor/board/system design. The default value
4269 you will find in any recent u-boot distribution in
4270 walnut.h should work for you. I'd set it to a value larger
4271 than your SDRAM module. If you have a 64MB SDRAM module, set
4272 it above 400_0000. Just make sure your board has no resources
4273 that are supposed to respond to that address! That code in
4274 start.S has been around a while and should work as is when
4275 you get the config right.
4277 -Chris Hallinan
4278 DS4.COM, Inc.
4280 It is essential to remember this, since it has some impact on the C
4281 code for the initialization procedures:
4283 * Initialized global data (data segment) is read-only. Do not attempt
4284 to write it.
4286 * Do not use any uninitialized global data (or implicitly initialized
4287 as zero data - BSS segment) at all - this is undefined, initiali-
4288 zation is performed later (when relocating to RAM).
4290 * Stack space is very limited. Avoid big data buffers or things like
4291 that.
4293 Having only the stack as writable memory limits means we cannot use
4294 normal global data to share information between the code. But it
4295 turned out that the implementation of U-Boot can be greatly
4296 simplified by making a global data structure (gd_t) available to all
4297 functions. We could pass a pointer to this data as argument to _all_
4298 functions, but this would bloat the code. Instead we use a feature of
4299 the GCC compiler (Global Register Variables) to share the data: we
4300 place a pointer (gd) to the global data into a register which we
4301 reserve for this purpose.
4303 When choosing a register for such a purpose we are restricted by the
4304 relevant (E)ABI specifications for the current architecture, and by
4305 GCC's implementation.
4307 For PowerPC, the following registers have specific use:
4308 R1: stack pointer
4309 R2: reserved for system use
4310 R3-R4: parameter passing and return values
4311 R5-R10: parameter passing
4312 R13: small data area pointer
4313 R30: GOT pointer
4314 R31: frame pointer
4316 (U-Boot also uses R12 as internal GOT pointer. r12
4317 is a volatile register so r12 needs to be reset when
4318 going back and forth between asm and C)
4320 ==> U-Boot will use R2 to hold a pointer to the global data
4322 Note: on PPC, we could use a static initializer (since the
4323 address of the global data structure is known at compile time),
4324 but it turned out that reserving a register results in somewhat
4325 smaller code - although the code savings are not that big (on
4326 average for all boards 752 bytes for the whole U-Boot image,
4327 624 text + 127 data).
4329 On ARM, the following registers are used:
4331 R0: function argument word/integer result
4332 R1-R3: function argument word
4333 R9: platform specific
4334 R10: stack limit (used only if stack checking is enabled)
4335 R11: argument (frame) pointer
4336 R12: temporary workspace
4337 R13: stack pointer
4338 R14: link register
4339 R15: program counter
4341 ==> U-Boot will use R9 to hold a pointer to the global data
4343 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4345 On Nios II, the ABI is documented here:
4346 http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4348 ==> U-Boot will use gp to hold a pointer to the global data
4350 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4351 to access small data sections, so gp is free.
4353 On NDS32, the following registers are used:
4355 R0-R1: argument/return
4356 R2-R5: argument
4357 R15: temporary register for assembler
4358 R16: trampoline register
4359 R28: frame pointer (FP)
4360 R29: global pointer (GP)
4361 R30: link register (LP)
4362 R31: stack pointer (SP)
4363 PC: program counter (PC)
4365 ==> U-Boot will use R10 to hold a pointer to the global data
4367 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4368 or current versions of GCC may "optimize" the code too much.
4370 On RISC-V, the following registers are used:
4372 x0: hard-wired zero (zero)
4373 x1: return address (ra)
4374 x2: stack pointer (sp)
4375 x3: global pointer (gp)
4376 x4: thread pointer (tp)
4377 x5: link register (t0)
4378 x8: frame pointer (fp)
4379 x10-x11: arguments/return values (a0-1)
4380 x12-x17: arguments (a2-7)
4381 x28-31: temporaries (t3-6)
4382 pc: program counter (pc)
4384 ==> U-Boot will use gp to hold a pointer to the global data
4386 Memory Management:
4387 ------------------
4389 U-Boot runs in system state and uses physical addresses, i.e. the
4390 MMU is not used either for address mapping nor for memory protection.
4392 The available memory is mapped to fixed addresses using the memory
4393 controller. In this process, a contiguous block is formed for each
4394 memory type (Flash, SDRAM, SRAM), even when it consists of several
4395 physical memory banks.
4397 U-Boot is installed in the first 128 kB of the first Flash bank (on
4398 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4399 booting and sizing and initializing DRAM, the code relocates itself
4400 to the upper end of DRAM. Immediately below the U-Boot code some
4401 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4402 configuration setting]. Below that, a structure with global Board
4403 Info data is placed, followed by the stack (growing downward).
4405 Additionally, some exception handler code is copied to the low 8 kB
4406 of DRAM (0x00000000 ... 0x00001FFF).
4408 So a typical memory configuration with 16 MB of DRAM could look like
4409 this:
4411 0x0000 0000 Exception Vector code
4412 :
4413 0x0000 1FFF
4414 0x0000 2000 Free for Application Use
4415 :
4416 :
4418 :
4419 :
4420 0x00FB FF20 Monitor Stack (Growing downward)
4421 0x00FB FFAC Board Info Data and permanent copy of global data
4422 0x00FC 0000 Malloc Arena
4423 :
4424 0x00FD FFFF
4425 0x00FE 0000 RAM Copy of Monitor Code
4426 ... eventually: LCD or video framebuffer
4427 ... eventually: pRAM (Protected RAM - unchanged by reset)
4428 0x00FF FFFF [End of RAM]
4431 System Initialization:
4432 ----------------------
4434 In the reset configuration, U-Boot starts at the reset entry point
4435 (on most PowerPC systems at address 0x00000100). Because of the reset
4436 configuration for CS0# this is a mirror of the on board Flash memory.
4437 To be able to re-map memory U-Boot then jumps to its link address.
4438 To be able to implement the initialization code in C, a (small!)
4439 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4440 which provide such a feature like), or in a locked part of the data
4441 cache. After that, U-Boot initializes the CPU core, the caches and
4442 the SIU.
4444 Next, all (potentially) available memory banks are mapped using a
4445 preliminary mapping. For example, we put them on 512 MB boundaries
4446 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4447 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4448 programmed for SDRAM access. Using the temporary configuration, a
4449 simple memory test is run that determines the size of the SDRAM
4450 banks.
4452 When there is more than one SDRAM bank, and the banks are of
4453 different size, the largest is mapped first. For equal size, the first
4454 bank (CS2#) is mapped first. The first mapping is always for address
4455 0x00000000, with any additional banks following immediately to create
4456 contiguous memory starting from 0.
4458 Then, the monitor installs itself at the upper end of the SDRAM area
4459 and allocates memory for use by malloc() and for the global Board
4460 Info data; also, the exception vector code is copied to the low RAM
4461 pages, and the final stack is set up.
4463 Only after this relocation will you have a "normal" C environment;
4464 until that you are restricted in several ways, mostly because you are
4465 running from ROM, and because the code will have to be relocated to a
4466 new address in RAM.
4469 U-Boot Porting Guide:
4470 ----------------------
4472 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4473 list, October 2002]
4476 int main(int argc, char *argv[])
4477 {
4478 sighandler_t no_more_time;
4480 signal(SIGALRM, no_more_time);
4481 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4483 if (available_money > available_manpower) {
4484 Pay consultant to port U-Boot;
4485 return 0;
4486 }
4488 Download latest U-Boot source;
4490 Subscribe to u-boot mailing list;
4492 if (clueless)
4493 email("Hi, I am new to U-Boot, how do I get started?");
4495 while (learning) {
4496 Read the README file in the top level directory;
4497 Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4498 Read applicable doc/README.*;
4499 Read the source, Luke;
4500 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
4501 }
4503 if (available_money > toLocalCurrency ($2500))
4504 Buy a BDI3000;
4505 else
4506 Add a lot of aggravation and time;
4508 if (a similar board exists) { /* hopefully... */
4509 cp -a board/<similar> board/<myboard>
4510 cp include/configs/<similar>.h include/configs/<myboard>.h
4511 } else {
4512 Create your own board support subdirectory;
4513 Create your own board include/configs/<myboard>.h file;
4514 }
4515 Edit new board/<myboard> files
4516 Edit new include/configs/<myboard>.h
4518 while (!accepted) {
4519 while (!running) {
4520 do {
4521 Add / modify source code;
4522 } until (compiles);
4523 Debug;
4524 if (clueless)
4525 email("Hi, I am having problems...");
4526 }
4527 Send patch file to the U-Boot email list;
4528 if (reasonable critiques)
4529 Incorporate improvements from email list code review;
4530 else
4531 Defend code as written;
4532 }
4534 return 0;
4535 }
4537 void no_more_time (int sig)
4538 {
4539 hire_a_guru();
4540 }
4543 Coding Standards:
4544 -----------------
4546 All contributions to U-Boot should conform to the Linux kernel
4547 coding style; see the kernel coding style guide at
4548 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
4549 script "scripts/Lindent" in your Linux kernel source directory.
4551 Source files originating from a different project (for example the
4552 MTD subsystem) are generally exempt from these guidelines and are not
4553 reformatted to ease subsequent migration to newer versions of those
4554 sources.
4556 Please note that U-Boot is implemented in C (and to some small parts in
4557 Assembler); no C++ is used, so please do not use C++ style comments (//)
4558 in your code.
4560 Please also stick to the following formatting rules:
4561 - remove any trailing white space
4562 - use TAB characters for indentation and vertical alignment, not spaces
4563 - make sure NOT to use DOS '\r\n' line feeds
4564 - do not add more than 2 consecutive empty lines to source files
4565 - do not add trailing empty lines to source files
4567 Submissions which do not conform to the standards may be returned
4568 with a request to reformat the changes.
4571 Submitting Patches:
4572 -------------------
4574 Since the number of patches for U-Boot is growing, we need to
4575 establish some rules. Submissions which do not conform to these rules
4576 may be rejected, even when they contain important and valuable stuff.
4578 Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4580 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4581 see https://lists.denx.de/listinfo/u-boot
4583 When you send a patch, please include the following information with
4584 it:
4586 * For bug fixes: a description of the bug and how your patch fixes
4587 this bug. Please try to include a way of demonstrating that the
4588 patch actually fixes something.
4590 * For new features: a description of the feature and your
4591 implementation.
4593 * For major contributions, add a MAINTAINERS file with your
4594 information and associated file and directory references.
4596 * When you add support for a new board, don't forget to add a
4597 maintainer e-mail address to the boards.cfg file, too.
4599 * If your patch adds new configuration options, don't forget to
4600 document these in the README file.
4602 * The patch itself. If you are using git (which is *strongly*
4603 recommended) you can easily generate the patch using the
4604 "git format-patch". If you then use "git send-email" to send it to
4605 the U-Boot mailing list, you will avoid most of the common problems
4606 with some other mail clients.
4608 If you cannot use git, use "diff -purN OLD NEW". If your version of
4609 diff does not support these options, then get the latest version of
4610 GNU diff.
4612 The current directory when running this command shall be the parent
4613 directory of the U-Boot source tree (i. e. please make sure that
4614 your patch includes sufficient directory information for the
4615 affected files).
4617 We prefer patches as plain text. MIME attachments are discouraged,
4618 and compressed attachments must not be used.
4620 * If one logical set of modifications affects or creates several
4621 files, all these changes shall be submitted in a SINGLE patch file.
4623 * Changesets that contain different, unrelated modifications shall be
4624 submitted as SEPARATE patches, one patch per changeset.
4627 Notes:
4629 * Before sending the patch, run the buildman script on your patched
4630 source tree and make sure that no errors or warnings are reported
4631 for any of the boards.
4633 * Keep your modifications to the necessary minimum: A patch
4634 containing several unrelated changes or arbitrary reformats will be
4635 returned with a request to re-formatting / split it.
4637 * If you modify existing code, make sure that your new code does not
4638 add to the memory footprint of the code ;-) Small is beautiful!
4639 When adding new features, these should compile conditionally only
4640 (using #ifdef), and the resulting code with the new feature
4641 disabled must not need more memory than the old code without your
4642 modification.
4644 * Remember that there is a size limit of 100 kB per message on the
4645 u-boot mailing list. Bigger patches will be moderated. If they are
4646 reasonable and not too big, they will be acknowledged. But patches
4647 bigger than the size limit should be avoided.